Book of Abstracts

13TH INTERNATIONAL SYMPOSIUM ON EQUATORIAL AERONOMY

BOOK OF ABSTRACTS

March 12-16, 2012 Paracas, Peru ISEA13 - 13th International Symposium on Equatorial Aeronomy

Table of Contents

ABOUT ISEA ...... 2

PREVIOUS ISEA VENUES ...... 2

COMMITTEES ...... 3

ISEA13 SCHEDULE ...... 4

LIST OF PARTICIPANTS ...... 5

Session 1 IRREGULARITY PHYSICS ...... 9

Session 2 E AND F REGION COUPLING (LOW AND MID LATITUDE COUPLING) . . . . 30

Session 3 WAVE PROPAGATION BETWEEN LOW/MIDDLE ATMOSPHERE AND IONO- SPHERE ...... 34

Session 4 PLASMA NEUTRAL COUPLING ...... 51

Session 5 LOW AND MID LATITUDE AERONOMY AND ELECTRODYNAMICS ...... 58

Session 6 IONOSPHERIC STORMS AND SPACE WEATHER EFFECTS AT LOW AND MID LATITUDES ...... 81

Session 7 NEW TECHNIQUES, EXPERIMENTS, CAMPAIGNS, AND RESULTS ...... 97

Session 8 FUTURE TRENDS AND CHALLENGES ...... 120

AUTHOR INDEX ...... 125

1 ISEA13 - 13th International Symposium on Equatorial Aeronomy

ABOUT ISEA

The International Symposium on Equatorial Aeronomy (ISEA) is an event organized approximately every three to four years and is a major event in the field of upper atmospheric and ionospheric science, gathering around 150 scientists from all over the world interested in studying the low latitude atmosphere and ionosphere and the coupling with other latitudinal and altitudinal regions. The ISEA represents an opportunity for scientists to share their most recent research results and progress as well as discuss possibilities for future campaigns and experiments. Its objective is to bring together the leaders in the field of equatorial, low-, and mid-latitude aeronomy to advance our knowledge about these regions of the Earth’s atmosphere. The 13th International Symposium on Equatorial Aeronomy will be held from March 12 to 16, 2012 at the La Hacienda Bahia Paracas Hotel, in Peru (near Ica). In addition to the ISEA 13 meeting, in 2012, the international scientific community will celebrate two important events:

• The 50 years from the ﬁrst ISEA meeting which took place in Huaychulo, Peru (1962);

• The 50th Anniversary of the Jicamarca Radio Observatory, Peru (1962); the main event of this celebration will be held right after ISEA13 on March 17, 2012 at the Jicamarca Radio Observatory. Celebration activities can be ﬁnd at http://jro.igp.gob.pe/jro50.

PREVIOUS ISEA VENUES

• ISEA-12 2008 Creete, Greece - AG, 27, 2009. 33 papers.

• ISEA-11 2005 Taipei, Taiwan - AG, 24(6), 2006. 18 papers.

• ISEA-10 2000 Antalya Turkey - JASTP, 64(12-14), 2002. 30 papers.

• ISEA-9 1995 Bali, Indonesia - JASTP, 59(13), 1997. 20 papers.

• ISEA-8 1990 Tucuman, Argentina - JATP, 53(8), 1991. 10 papers.

• ISEA-7 1984 Hong Kong - JATP, 47(10), 1985. 34 papers.

• ISEA-6 1980 Aguadilla, Puerto Rico - JATP, 43(5/6 & 8), 1981. 40 papers.

• ISEA-5 1976 Townsville, Australia - JATP, 39(9/10), 1977. 35 papers.

• ISEA-4 1972 Ibadan, Nigeria - JATP, 35(6), 1973. 26 papers.

• ISEA-3 1969 Ahmedabad, India.

• ISEA-2 1965 Rio de Janeiro, Brazil.

• ISEA-1 1962 Huaychulo, Peru.

AG = Annales Geophysicae JASTP = Journal of Atmospheric and Solar-Terrestrial Physics JATP = Journal of Atmospheric and Terrestrial Physics

2 ISEA13 - 13th International Symposium on Equatorial Aeronomy

COMMITTEES

International Organizing Committee

• Jorge L. Chau (Radio Observatorio de Jicamarca, Instituto Geofísico del Perú, Perú)

• Archana Bhattacharyya (Indian Institute of Geomagnetism, India)

• Clezio M. Denardini (Instituto Nacional de Pesquisas Espacias, Brasil)

• David L. Hysell (Cornell University, USA)

• Erhan Kudeki (University of Illinois, USA)

• Jonathan Makela (University of Illinois, USA)

• Kazuo Shiokawa (Nagoya University, Japan)

Local Organizing Committee

• Marco Milla (Radio Observatorio de Jicamarca)

• Benjamín Castañeda (Pontiﬁcia Universidad Católica del Perú)

• Ricardo Coloma (Ciencia Internacional)

• William Ipanaque (Universidad de Piura)

• Mara Seminario (Tourism Activities)

• Ken Takahashi (Instituto Geofísico del Perú)

• Hector Velarde (Hoteles La Hacienda)

Science Advisory Committee

A. Bhattacharyya, J. L. Chau, C. M. Denardini, L. Goncharenko, S. González, M. Hagan, R. Heelis, D. L. Hysell, E. Kudeki, C. La Hoz, M. Larsen, J. Makela, C. Martinis, N. Maruyama, J. Meriwether, M. Milla, E. Nossa, M. Oppenheim, E. Pacheco, D. Pallamraju, D. Pancheva, A. K. Patra, R. Pfaﬀ, S. Raizada, P. Roddy, D. Scipion, K. Shiokawa, H. Takahashi, J. Urbina, C. Valladares, R. F. Woodman, M. Yamamoto.

3 ISEA13 - 13th International Symposium on Equatorial Aeronomy

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

4 ISEA13 - 13th International Symposium on Equatorial Aeronomy

LIST OF PARTICIPANTS

Last Name First Name E-mail Abdu Mangalathayil A. [email protected] Anderson David [email protected] Araujo Luciana [email protected] Aveiro Henrique [email protected] Bagiya Mala [email protected] Balsley Ben [email protected] Benhke Richard [email protected] Bertoni Fernando [email protected] Bhattacharyya Archana [email protected] Buriti da Costa Ricardo Arlen [email protected] Burrell Angeline [email protected] Calle Angela [email protected] Chakrabarty Dibyendu [email protected] Chau Jorge [email protected] Cherniak Iurii [email protected] Chu Yen Hsyang [email protected] Condori Luis [email protected] Cosgrove Russell [email protected] Coster Anthea [email protected] Crowley Geoff [email protected] Dao Eugene [email protected] De La Beaujardiere Odile [email protected] De La Cruz Ricardo Yvan [email protected] De La Jara César [email protected] De Paula Eurico [email protected] Denardini Clezio [email protected] Duggirala Pallam Raju [email protected] Dyrud Lars [email protected] Egito Fabio [email protected] Emery Barbara [email protected] Erickson Philip [email protected] Escate Riano [email protected] Euribe Ku Carlos Alberto [email protected] Fagundes Paulo Fagundes [email protected] Fang Tzu-Wei [email protected] Farley Donald [email protected] Fejer Bela [email protected] Felquer Fernando ff[email protected] Fentzke Jonathan [email protected] Ferradas Cristian [email protected] Forbes Jeffrey [email protected] Foster John [email protected] Fukushima Daisuke [email protected] Fuller-Rowell Tim [email protected] Galindo Freddy [email protected] Gerrard Andrew [email protected]

5 ISEA13 - 13th International Symposium on Equatorial Aeronomy

6 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Last Name First Name E-mail Oyekola Oyedemi [email protected] Pacheco Edgardo [email protected] Paulino Igo [email protected] Paulino Ana Roberta [email protected] Pfaff Robert Robert.F.Pfaff@nasa.gov Raizada Shikha [email protected] Raulin Jean Pierre [email protected] Ren Zhipeng [email protected] Rengifo Javier [email protected] Resende Laysa [email protected] Rios Victor [email protected] Ritter Patricia [email protected] Saito Akinori [email protected] Santos Angela [email protected] São Sabbas Fernanda [email protected] Scipion Danny [email protected] Sekar Ramanathan [email protected] Seran Elena [email protected] SG Sumod [email protected] Shiokawa Kazuo [email protected] Sidorova Larisa [email protected] Simoes Fernando [email protected] Sorbello Robert [email protected] Sripathi Samireddipalle ssripathi@rediffmail.com St-Maurice Jean-Pierre [email protected] Stolle Claudia [email protected] Stoneback Russell [email protected] Suarez Muñoz Daniel [email protected] Sunda Surendra [email protected] Swenson Gary [email protected] Takahashi Hisao [email protected] Taramona Jorge [email protected] Taylor Michael [email protected] Thu Trang Nguyen [email protected] Tisnado Gilberto gilberto@tecnofil.com.pe Tiwari Diwakar [email protected] Tsunoda Roland [email protected] Tuysuz Burak [email protected] Urbina Julio [email protected] Urco Miguel [email protected] Valladares Cesar [email protected] Vargas Fabio [email protected] Varney Roger [email protected] Vasyliunas Vytenis M. [email protected] Vierinen Juha [email protected] Vincent Robert [email protected] Vineeth C. [email protected] Vogel Ely Cláudia [email protected]

7 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Last Name First Name E-mail Woodman Ronald [email protected] Xiong Jiangang [email protected] Yamamoto Mamoru [email protected] Yee Jeng-Hwa [email protected] Yizengaw Endawoke [email protected] Yokoyama Tatsuhiro [email protected] Zakharenkova Irina [email protected] Zhao Biqiang [email protected]

8 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 1

IRREGULARITY PHYSICS

In the past few years, equatorial aeronomers have made signiﬁcant progress toward understanding the evolution of ionospheric plasma structures and irregularities encompassing scales ranging from meters to hundreds of kilometers. Through observations, simulations, and theory researchers are making steady progress toward understanding and modeling F-region equatorial plasma bubbles, midlatitude E- and F-region irregularities, meteor trail physics, and the old problem of the non-linear behavior of the Farley-Buneman and Gradient-Drift instabilities. New studies of 150-km echoes have given us a number of clues which should help scientists understand the origin of this enigmatic radar phenomenon. This session welcomes the submission of papers addressing recent experimental, computational and theoretical studies of E- and F-region plasma irregularities. This includes the formation, evolution, and nonlinear properties of km- to m- scales. Research addressing the day- to-day variability of spread F irregularities, including those detected by C/NOFS instruments, are appropriate for this session.

Conveners: Amit Patra, Meers Oppenheim, and Marco Milla

9 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - HIERARCHY OF PRO- plasma irregularities. Traditionally, simulations CESSES BEHIND F-REGION PLASMA of ionospheric plasma instabilities assume elec- DENSITY IRREGULARITIES trostatic physics and/or simplify the problem in two dimensions where dynamics along Earth’s David Hysell magnetic field lines are neglected. Explored are the electric and magnetic field signatures Cornell University, Ithaca, NY, USA of plasma irregularities resulting from current divergence, current flows, and Alfven waves as- Free energy in the F-region ionosphere sociated with plasma irregularity dynamics. can express itself in the form of plasma density irregularities which are key components of TYPE: ORAL space weather. The irregularities owe their DATE: 2012-03-12 – 14:55 existence to inhomogeneities in configuration space. Configuration space inhomogeneity includes gradients in ionospheric conductivity and ON THE EQUIPOTENTIAL FIELD drift velocity, which contribute together to in- LINE APPROXIMATION IN THE LOW- stability and irregularity formation. Conductiv- LATITUDE IONOSPHERE AND ITS IM- ity gradients along the magnetic field are over- PLICATION ON SPREAD F SIMULA- looked but can also factor in irregularity pro- TIONS duction. While F-region irregularities are typi- Henrique Aveiro and David Hysell cally driven directly at scale sizes of kilometers or larger, nonlinear mode coupling can excite Cornell University, Ithaca, NY, USA irregularities at scale sizes shorter than the ion An initial boundary value simulation of gyroradius. Mode coupling mainly takes the equatorial spread F (ESF) is taken using three form of steepening rather than a turbulent cas- different approaches for the computation of the cade and is typically highly intermittent. The electrostatic potential: equipotential geomag- salient features of mode coupling are conse- netic field line assumption (EFL), EFL with a quently more apparent in physical space than in correction due to the ambipolar electric field spectral representations. Magnetic aspect sen- (EFL-Amb), and the full three-dimensional so- sitivity measurements suggest that small-scale lution (3-D). The main issue we address is the field-aligned plasma density irregularities are degree to which it is possible to simulate the initially isotropic, becoming more field aligned background ionospheric current system and its as they dissipate. effects on ESF simulations given an appropriate specification of the initial conditions and TYPE: ORAL the forcing. The simulation results are com- DATE: 2012-03-12 – 14:35 pared to CHAMP magnetometer and ALTAIR radar observations.

3D ELECTROMAGNETIC PLASMA TYPE: ORAL MODEL: ELECTRIC AND MAGNETIC DATE: 2012-03-12 – 15:10 SIGNATURES OF PLASMA IRREGU- LARITIES DAY-TO-DAY VARIABILITY OF EQUA- Eugene Dao, Charlie Seyler, and Mike Kelley TORIAL SPREAD-F OBSERVED WITH GNU RADIO BEACON RECEIVER Cornell University, Ithaca, NY, USA (GRBR) IN ASIA AND AFRICA Presented are three dimensional electro- Mamoru Yamamoto1, Kensuke Hangyo1, S. magnetic model simulations of low-latitude Tulasi Ram2, and Roland Tsunoda3

10 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 Research Institute for Sustainable Hu- NASA Goddard Space Flight Center, Green- manosphere, Kyoto University, Japan belt, MD, USA 2 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, India The Vector Electric Field Investigation 3 SRI International, Menlo Park, CA, USA (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed Equatorial spread F (ESF) is intense iono- measurements of irregularities associated with spheric irregularity that occurs around the geo- the equatorial ionosphere and in particular with magnetic equator. It can cause intense scin- spread-F depletions. We present vector AC tillation to satellite-ground communications, electric field observations gathered on C/NOFS and serious error in the GPS measurements. that address a variety of key questions regard- The ESF has been a hot research topic of ing how plasma irregularities, from meter to the equatorial/low-latitude ionosphere for long kilometer scales, are created and evolve. The time. However, its day-to-day variability is talk focuses on occasions where the ionosphere not well understood. Now we deploy a very F-peak has been elevated above the C/NOFS wide network of GNU Radio beacon receivers satellite perigee of 400 km as solar activity has (GRBR) at low latitudinal regions over east increased. In particular, during the equinox pe- Africa, southeast Asia, and Pacific region, and riods of 2011, the satellite consistently jour- observe 150MHz/400MHz beacon signal from neyed below the F-peak whenever the orbit was C/NOFS and other polar-orbiting satellites. In in the region of the South Atlantic anomaly af- this paper, we use data from Bac Lieu, Viet- ter sunset. During these passes, data from the nam (9.29N, 105.71E, Dip Lat. 1.67N, obser- electric field and plasma density probes on the vations started in January 2009) and Bahirdar, satellite have revealed two types of instabilities Ethiopia (11.56N, 37.38E, Dip Lat. 3.93N, ob- which had not previously been observed in the servations started in March 2011). We discuss C/NOFS data set: The first is evidence for 400- relationships between day-to-day variability of 500km-scale bottomside “undulations” that ap- ESF with ionospheric structures, i.e., large- pear in the density and electric field data. In scale wave structure (LSWS), meridional sym- one case, these large scale waves are associated metry of the ionosphere density distribution, with a strong shear in the zonal E x B flow, as and VHF/UHF scintillation intensity. Occur- evidenced by variations in the meridional (out- rence of ESF is well correlated with enhanced ward) electric fields observed above and below LSWS events in the evening time. At Bahir- the F-peak. These undulations are devoid of dar, scintillation level is high, and very intense smaller scale structures in the early evening, LSWS events are found. Comparison of sta- yet appear at later local times along the same tistical results between two locations provides orbit associated with fully-developed spread-F useful information to attack longitudinal vari- with smaller scale structures. This suggests ability of the ESF. that they may be precursor waves for spread- F, driven by a collisional shear instability, fol- TYPE: ORAL lowing ideas advanced previously by researchers DATE: 2012-03-12 – 15:25 using data from the Jicamarca radar. A second result is the appearance of km-scale irregulari- ELECTRIC FIELD AND PLASMA DEN- ties that are a common feature in the electric SITY OBSERVATIONS OF IRREGULAR- field and plasma density data that also appear ITIES AND PLASMA INSTABILITIES IN when the satellite is near or below the F-peak THE LOW LATITUDE IONOSPHERE at night. The vector electric field instrument GATHERED BY THE C/NOFS SATEL- on C/NOFS clearly shows that the electric field LITE component of these waves is strongest in the zonal direction. These waves are strongly corre- Robert Pfaff, Henry Freudenreich, Doug Row- lated with simultaneous observations of plasma land, JeffKlenzing, and Carmen Liebrecht density oscillations and appear both with, and

11 ISEA13 - 13th International Symposium on Equatorial Aeronomy without, evidence of larger-scale spread-F de- of the irregularity. It is found that highly struc- pletions. These km-scale, quasi-coherent waves tured EPBs only appear on fluxtubes that reach strongly resemble the bottomside, sinusoidal to large apex heights. irregularities reported in the Atmosphere Ex- plorer satellite data set by Valladares et al. Besides the pressure gradient currents there [JGR, 88, 8025, 1983] and are believed to cause are also field-aligned currents (FAC) associated scintillations of VHF radiowaves. We interpret with EPBs. Such currents have been predicted these new observations in terms of fundamental by numerical models that take into account the plasma instabilities associated with the unsta- electrodynamic nature of the EPB evolution. ble, nighttime equatorial ionosphere. The existence of FACs has been confirmed by CHAMP magnetic field measurements. The TYPE: ORAL FACs are flowing primarily on the east and west DATE: 2012-03-12 – 15:40 flanks of the depleted fluxtubes. Up to 21:00 local time the FAC topology is well organized confirming the “shell-like” shape of depleted regions. After 22:00 LT the hemispheric symme- INVITED - IONOSPHERIC IRREGULAR- try disappears. ITIES AT LOW LATITUDES AND THEIR MAGNETIC SIGNATURES We will present instructive examples of magnetic signatures and try to make inferences Hermann Lühr and Jaeheung Park on the EPB evolution considering their electrodynamic features. Helmholtz Centre Potsdam, German Research Centre for Geosciences, Germany TYPE: ORAL DATE: 2012-03-12 – 15:55 Ionospheric irregularities at low latitudes have received a lot of attention because they can badly degrade GPS navigational signals or STUDY OF EQUINOCTIAL ASYMME- even disrupt them. The occurrence distribution TRY IN THE EQUATORIAL SPREAD F of these so-called equatorial plasma bubbles (ESF) IRREGULARITIES OVER INDIAN (EPB) has been studied based on ionospheric REGION USING MULTI-INSTRUMENT radar measurements, scintillation of GPS sig- OBSERVATIONS IN THE DESCENDING nals or in-situ satellite observations. Here we PHASE OF SOLAR CYCLE-23 are reporting about 10 years of CHAMP mea- Samireddipalle Sripathi, Bharati Kakad, and surements. Archana Bhattacharyya

The high-resolution magnetic field mea- Indian Institute of Geomagnetism, Navi Mum- surements performed by CHAMP make it pos- bai, India sible to study in detail the magnetic signatures associated with plasma bubbles. Most In this paper, we present the results of obvious is the increase of field strength inside a morphological study of Equatorial Spread F the depleted region of the EPB. The deficit of (ESF) irregularities over Indian region based plasma pressure is locally compensated by an mainly on observations of (a) amplitude scin- increase in magnetic pressure. This relation tillations on GPS L-band signal and Rate of has been used successfully for deriving the spa- TEC Index (ROTI) obtained using a network tial and temporal variations of the EPB occur- of GPS receivers and (b) amplitude scintilla- rence frequencies from magnetic field record- tions on a VHF signal using spaced receivers at ings. CHAMP is sampling the magnetic field Tirunelveli, an equatorial station. Occurrence at a rate of 50 Hz. These high-resolution data of both amplitude scintillations on the GPS have been used to resolve the smallest scales L1 signal and occurrence of significant ROTI

12 ISEA13 - 13th International Symposium on Equatorial Aeronomy recorded at several stations has been investi- 2. Why do rocket-borne magnetic field gated. The latitudinal extent of L-band scintil- measurements of the EEJ height disagree with lations shows that their strength is weak over theory (Gagnepain et al., 1977)? the dip equator but stronger over Equatorial Ionization Anomaly (EIA) region, preferentially 3. Why does the wave phase velocity satu- during vernal equinox. We find an equinoctial rate at Cs and does not equal the electron drift asymmetry in both the occurrence of scintil- velocity? lations and ROTI wherein their occurrence is greater in the vernal equinox than in the au- 4. For large zonal electric fields (>1 tumn equinox. Attempts have been made to mV/m), why is the magnetic field of the EEJ understand the asymmetry in latitudinal extent smaller than that extrapolated linearly from using maximum cross-correlation (CI) of inten- smaller electric fields? That is, what is the sity fluctuations obtained from the VHF spaced origin of the anomalously low conductivity for receivers observations. The observations sug- large driving fields? gest that occurrence of CI less than 0.5 is more in the vernal equinox than in the autumn 5. Why is the measured magnetic field equinox suggesting that the maximum height of lower than predicted by classical theory? the Equatorial Plasma Bubbles (EPBs) during vernal equinox may be higher than that dur- 6. Why are the phase velocities of the ing autumn equinox. TIMED/GUVI retrieved longest wavelength plasma waves square-wave peak electron density during the same period in nature (Kudeki et al., 1984) while associated also indicates that background electron den- horizontal-wave electric fields that are highly sity is higher and more symmetric during ver- nonlinear also appear as square-waves (Pfaffet nal equinox than autumn equinox. Hence, our al., 1987)? results suggest that background electron density may be playing a vital role in creating the We will examine why these issues are so dif- equinoctial asymmetry. ficult to answer, and therefore why they are so interesting, and then consider the solutions. TYPE: ORAL DATE: 2012-03-12 – 16:15 TYPE: ORAL DATE: 2012-03-12 – 17:00 A TUTORIAL: SOLUTIONS TO THE LAST OUTSTANDING EQUATORIAL ELECTROJET PROBLEMS ON NONLINEAR FARLEY-BUNEMAN IRREGULARITIES Michael Kelley Abdelhaq M. Hamza Cornell University, Ithaca, NY, USA University of New Brunswick, New Brunswick, There are six fundamental problems with Canada equatorial electrojet (EEJ) theory that have been very difficult to solve, even 50 years af- One of the most fundamental challenges of ter they were posed. In summary, they are: ionospheric physics is to explain why the largest amplitude structures tend to move at phase 1. Why is the phase velocity of plasma speeds that do not exceed on average the linear waves responsible for radar scatter independent theory threshold? To provide a solution one has of zenith angle in defiance of linear plasma the- to rely on nonlinear theory in order to study the ory for acoustic waves (first reported in 1964 development and evolution of nonlinear iono- (Farley et al., 1963)? spheric structures. We propose to study the

13 ISEA13 - 13th International Symposium on Equatorial Aeronomy development and evolution of nonlinear, large- is same for both the days. This indicates the amplitude, intermittent E-region plasma struc- reduction in the vertical electric field on annu- tures. The results of a model based on the non- lar solar eclipse day. Further, an evidence for linear coupling between three and four Farley- the polarity variation in the E-region vertical Buneman (FB) waves in three dimensions (3D) electric field during an earlier total solar eclipse will be presented. We are able to recover the event (16 February 1980) is obtained. In addi- 2D results reported in the literature as a limit tion, an investigation is carried out using avail- case in our study, and we are able to show that able rocket, radar and ground based magne- both the three-wave and the four-wave interac- tometer measurements to comprehensively un- tions play a significant role as far as nonlinear derstand the generation of plasma waves in saturation mechanisms are concerned. We will the E-region. This investigation revealed that also attempt to describe the impact of nonlin- the generation of the streaming waves is sen- ear FB structures on the electron anomalous re- sitive to drift of the dip equator from Thumba sistivity and consequently on transport in gen- obtained using systematic magnetometer mea- eral and heating in particular. surements. The importance of these scientific results will be highlighted in this paper. TYPE: ORAL DATE: 2012-03-12 – 17:20 TYPE: ORAL DATE: 2012-03-12 – 17:35

E-REGION PLASMA WAVES OVER THUMBA, INDIA: RECENT RESULTS METEORIC DUST EFFECT ON THE E- REGION PLASMA INSTABILITY MECH- Ramanathan Sekar ANISMS

Physical Research Laboratory, Ahmedabad, In- Polinaya Muralikrishna dia Instituto Nacional de Pesquisas Espaciais - It is well known that streaming plasma INPE, Sao Jose dos Campos, SP, Brazil waves and gradient drift plasma waves are excited in the E-region of the ionosphere over It is known that the meteoric dust particles the dip equator location. These plasma waves play an important role in the electrodynamics over Thumba, India, a location closer to the of the E-region plasma. Large amounts of dust dip equator, have been investigated over the particles with average sizes of about 0.1m with years by rocket borne in situ probes (Prakash number densities of up to several thousands per et al., 1972; Sastry, 1970) and ground based cubic centimeter and charge densities of the VHF (Reddy et al., 1987; Krishnamurthy et same order have been experimentally detected al., 1998) and HF radars (Janardhanan et al., in the lower E-region altitudes. In some parts 2001; Tiwari et al., 2003). Recently, two RH- of the dust layers it was found that the nega- 300 MKII rockets containing Langmuir probes tive charge density on dusts was so large that were flown from Thumba on 15 and 16 January the number of free electrons was significantly 2010 to investigate the equatorial E-region of reduced there, since the dust acted as a sink the ionosphere. The results obtained from this for electrons, thus causing electron bite outs. rocket flight campaign are compared with the Recent studies show the possible role of neu- previous results obtained from the same loca- tral as well as charged dust particles of submi- tion using various techniques. The amplitudes cron size in altering the conductivity parame- of gradient drift waves were found to be less on ters in the equatorial E-region through the col- an annular solar eclipse day (15 January 2010) lision frequencies. In the upper E-region the compared to the control day (16 January 2010) dust particles are not very effective in captur- in a region where the electron density gradient ing the ambient electrons and so do not affect

14 ISEA13 - 13th International Symposium on Equatorial Aeronomy the quase neutrality of the plasma. But they the potential to help us understand the aeron- can alter the effective collision frequencies of omy of MLT region and might also help in in- the ambient electrons in this region by a factor terpretation of a variety of upper atmospheric as high as 4. They can also reduce significantly phenomenon including Polar Mesospheric Sum- the growth rate and amplitude of plasma irreg- mer Echoes (PMSE) and NLC (Noctilucent ularities in this region. In the lower E-region Clouds). Though there have been numerous the dust particles can affect significantly the reports of fragmentation in meteoroids from electrical conductivities. When exist in suffi- most of the HPLA radars (Arecibo, EISCAT, cient numbers, charged dust particles can even PFISR, RISR, ALTAIR), the apparent lack of reverse the ambient vertical polarization elec- fragmentation in meteor observations from the tric field in the lower E-region altitudes. This Jicamarca Radio Observatory (JRO) presents can affect the plasma instability mechanisms a mystery although electrojet contamination like Cross-Field Instability and Two-Stream In- and the ready formation of range-spread trail- stability that operate in the E-region. Assum- echoes (RSTE) cloud interpretation. We re- ing a simple exponential model for the dust port results from two sets of April 2010 obser- layer, the role of these dust particles in altering vations at JRO during which an uncoded 20 the E-region electrodynamics by affecting the ?sec pulse was used for meteor observations. collision and conductivity parameters is inves- This observing mode parallels that used with tigated here. the Arecibo 46.8 MHz radar that has similar sensitivity to JRO in interferometry mode thus TYPE: ORAL allowing direct comparisons. Our findings in- DATE: 2012-03-12 – 17:50 clude meteoroid fragmentation results that are similar to those from the Arecibo VHF radar and lead to the conclusion that fragmentation METEOROID FRAGMENTATION AND is observed at Jicamarca. We additionally re- HIGH-ALTITUDE METEORS OB- port on high-altitude meteor events that are SERVED AT JICAMARCA surprisingly common, offer insight into sputter- John Mathews1, Boyi Gao1, Julio Urbina2, ing as a source of the meteor ionization, and Freddy Galindo2, and Akshay Malhotra3 perhaps indicate the unique importance of the magnetic field geometry in these head-echo ob- 1 Pennsylvania State University, State Park, servations. Finally, we also offer interesting PA, USA new results on meteor events “painting” low- 2 Communications and Space Sciences Labora- altitude ionization layers. tory, Pennsylvania State University, University Park, PA, USA TYPE: ORAL 3 Symbiosis Institute of Technology, India DATE: 2012-03-12 – 18:05

One of the most exciting, and even controversial, developments in the meteor physics THE ROLE OF TURBULENCE ON THE community in the past few years has been the EVOLUTION OF SPECULAR METEOR conﬁrmation of fragmentation in perhaps the ECHOES majority of meteoroids observed by many of the High Power Large Aperture (HPLA) radars. Freddy Galindo1, Julio Urbina1, Lars Dyrud2, That meteoroid fragmentation can be quanti- and Johathan Fentzke2 tatively observed using HPLA radar assumes vital signiﬁcance as it provides additional in- 1 Communications and Space Sciences Labora- sight into the mass-loss mechanisms of the bil- tory, Pennsylvania State University, University lions of meteoroids that strike the Earth’s at- Park, PA, USA mosphere annually. The thorough understand- 2 Applied Physics Laboratory, John Hopkins ing of his aspect of space weather also has University, MD, USA

15 ISEA13 - 13th International Symposium on Equatorial Aeronomy

We report initial results of a numerical 2 Communications and Space Sciences Labora- model developed to study the effect of turbu- tory, Pennsylvania State University, University lences on the evolution of underdense specu- Park, PA, USA lar meteor trails. Understanding meteor trail plasma turbulence is important because turbu- We present the first global simulations on lent meteor trails are visible as non-specular the occurrence of meteor trail plasma irregu- trails to coherent radars, and turbulence in- larities to incorporate the electrodynamics of fluences the growth of specular meteor radar the auroral zone and the equatorial electro-jet. trails, particularly regarding the inference of The electojet regions of the earth are pecu- mesospheric temperatures from trail diffusion liar locations for meteor trail evolution because rates, and their usage for meteor scatter com- strong electric fields dominate the meteor trail munication systems. The architecture of the evolution by generating mini-electrojets with numerical model traces meteor trail evolution even stronger polarization fields. As the results from ablation and ionization processes through show, electrojet meteors, such as those near the the creation of the actual specular meteor echo. magnetic equator are far more likely to be tur- Thus, this meteor model represents a valuable bulent than other geographic locations where tool for the analysis of specular meteor physics. neutral winds dominate polarization fields. Un- We describe and compare our simulation re- derstanding meteor trail plasma turbulence is sults with the general characteristics of meteor important in part because turbulent meteor echoes detected with two different data radar trails are visible as non-specular trails to coher- systems. The first radar operated at 50 MHz ent radars. Turbulence also influences the evo- with moderate peak power of about 30 kW and lution of specular radar meteor trails; this fact was oriented perpendicular to the Earth’s mag- is important for the inference of mesospheric netic field while the second radar also operated temperatures from the trail diffusion rates, and at 50 MHz but with relatively low peak power their usage for meteor burst communication. of about 5 kW. The latter radar was configured We provide evidence of the significant effect in classical all-sky mode observation. By com- that neutral atmospheric winds and ionospheric paring data from the different meteor systems, plasma density, and ionospheric electric fields our preliminary studies illustrate the significant have on the variability of meteor trail evolu- effect that neutral atmospheric winds and den- tion and on the observation of non-specular me- sity, and ionospheric plasma density have on teor trails, and discuss in particular how meteor the variability of meteor trail evolution and the trails can be used to remote sense the equato- observation of non- specular meteor trails, and rial electojet. demonstrate that trails are far less likely to become and remain turbulent in daylight, ex- TYPE: ORAL plaining several observational trends using non- DATE: 2012-03-12 – 18:35 specular and specular meteor trails.

TYPE: ORAL POST-SUNSET IRREGULARITIES IN DATE: 2012-03-12 – 18:20 THE EQUATORIAL UPPER E-REGION Ronald Ilma, David Hysell, and Henrique Aveiro INFLUENCE OF IONOSPHERIC ELEC- Cornell University, Ithaca, NY, USA TROJETS ON METEOR TRAIL EVOLU- TION Large-scale plasma waves have been de- Lars Dyrud1, Johathan Fentzke1, and Julio tected by the low-power JULIA radar at Jica- Urbina2 marca in the last decade. These waves, which occur in the upper E-region at twilight, are a 1 Applied Physics Laboratory, John Hopkins new class of equatorial irregularities and they University, MD, USA have not been previously predicted. Although

16 ISEA13 - 13th International Symposium on Equatorial Aeronomy the source of these echoes have not been pre- the radar pointed perpendicular to the mag- cisely determined, the current radar database, netic field (B). Recent studies at Jicamarca in- obtained under both single-line interferometric dicate that most of 150-km echoes come from and aperture synthesis imaging modes, tenta- waves that have been enhanced above waves tively suggest that they are associated with a in thermal equilibrium, i.e., they are also ob- gradient drift instability capable of generating served when the radar points off-perpendicular these large-scale primary waves. The statisti- to B (Oblique). The physical mechanisms gen- cal analysis of the single-baseline interferome- erating these echoes are still elusive. In this try observations reveals that the probability to work we present results of the East-West (EW) detect these echoes is relatively higher during structure of both echoes: Perpendicular and equinox than solstice, in the height range from Oblique, using observations were dual beams 120 to 140 km during and after sunset. Prelim- and aperture synthesis imaging techniques were inary results from computer simulations code, employed. By the time of the conference, we which has been previously applied to Spread- expect that the new observations that involve F studies satisfactorily, show the emergence of concurrent measurements of the oblique and waves in similar spatial and temporal condi- perpendicular echoes as well as their EW struc- tions to those observed echoes. The numerical ture, will reveal new insights on the complexity model produces nice gradient drift waves in the of these echoes. topside of the electrojet. The simulation results also present a relative density fluctuations of 10 TYPE: ORAL percent or so. From the same results, waves in DATE: 2012-03-13 – 08:15 the E-F valley propagate westward and downward and look like the ones we see from time INCOHERENT SCATTER AND SOUND- to time in this physical regime. What’s most ING MEASUREMENTS IN THE 150 KM interesting about them is that they exhibit fi- REGION OF THE EQUATORIAL IONO- nite parallel wavenumber vector. This, and the SPHERE existence of a parallel density gradient, are the keys to their growth. Erhan Kudeki1, Jorge Chau2, and Marco Milla2

1 TYPE: ORAL University of Illinois at Urbana-Champaign, DATE: 2012-03-13 – 08:00 Urbana, IL USA 2 Radio Observatorio de Jicamarca, Instituto Geofísico del Perú, Lima, Perú ON THE EAST-WEST STRUCTURE OF Recent VIPIR measurements at Jicarmaca 150-KM PERPENDICULAR AND OFF- show indications of electron density structures PERPENDICULAR TO B ECHOES OVER and ﬂuctuations in the upper E-region. These JICAMARCA structures can be associated with and possibly cause the generation of the 150 km irregular- 1 2 3 Jorge Chau , David Hysell , Erhan Kudeki , ities observed in the equatorial ionosphere. In 1 1 Marco Milla , and Miguel Urco this talk we will present incoherent scatter radar data collected using the Jicamarca Faraday ro- 1 Radio Observatorio de Jicamarca, Instituto tation mode concurrently with VIPIR observa- Geofísico del Perú, Lima, Perú tions. The ISR data also support the conjecture 2 Cornell University, Ithaca, NY, USA that the 150 km altitude region may have struc- 3 University of Illinois at Urbana-Champaign, tured electron densities at intermediate scales Urbana, IL USA related to the generation of the meter scale 150 km irregularities. Also, recent multi-beam and For many years 150-km echoes appeared to multi-static measurement results from the re- come from ﬁeld-aligned irregularities, i.e., when gion will be presented.

17 ISEA13 - 13th International Symposium on Equatorial Aeronomy

TYPE: ORAL Tiger J.Y. Liu1, S. P. Chen1, G. S. Chang2, and DATE: 2012-03-13 – 08:30 C. H. Lin3

1 Institute of Space Science, National Central CHARACTERISTICS OF EQUATORIAL University, Taiwan PLASMA BUBBLES OBSERVED FROM 2 National Space Organization, Taiwan INDIAN SECTOR DURING WINTER 3 Department of Earth Sciences, Cheng Kung MONTHS OF DEEP SOLAR MINIMUM University, Taiwan Viswanathan Lakshmi Narayanan and Subra- manian Gurubaran The FORMOSAT-3/COSMIC (F3/C) constellation lunched on 15 April 2006, which con- Indian Institute of Geomagnetism, Navi Mum- sists of six micro-satellites in the low-earth or- bai, India bit, is capable of monitoring the troposphere and ionosphere by using the powerful technique All-sky airglow imaging observations of OI of radio occultation. With more than 2000 ob- 630 nm emissions from low latitude Indian sec- servations per day, it provides an excellent op- tor during January to March 2008 revealed portunity to monitor three-dimensional struc- presence of plasma bubbles on 17 nights. The tures and dynamics of the ionospheric scintil- bubbles observed on 8 of the nights correspond lations during 2006-2011. The global F3/C to geomagnetically quiet period and those ob- S4 index are subdivided and examined in var- served on remaining 9 nights correspond to dis- ious latitudes, longitudes, altitudes, and sea- turbed period. Herein, we discuss the char- sons. The F-region scintillations in the equa- acteristics of the observed bubbles based on torial and low-latitude ionosphere start around the following parameters: drift speed, interde- post-sunset period and often persist till post- pletion distances, tilts, bifurcations and merg- midnight hours (0300 MLT, magnetic local ing. We have utilized simultaneous ionosonde time) during the March and September equinox measurements made from dip equatorial site as well as December Solstice seasons. The E- Tirunelveli. The variations of base height of region scintillations reveal a clear solar zenith F layer (h’F) observed over dip equator clearly effect and yield pronounced intensities in mid- showed that PRE has no significant role in the latitudes during the Summer Solstice seasons, formation of the observed bubbles, at least dur- which are well correlated with occurrences of ing this solar epoch. Plasma bubbles were the sporadic E-layer. There is no obvious scin- even observed on those nights with no post tillation activity observed in the high-latitude sunset rise of F region ionosphere. In ad- ionosphere. dition to the eastward drifts, westward drifts are also observed during disturbed geomag- TYPE: ORAL netic conditions. Moreover, the tilts of the ob- DATE: 2012-03-13 – 09:00 served bubbles were higher during geomagnetically disturbed conditions. No significant variations were found in the range of interdepletion FORECASTING L BAND SCINTILLA- distances observed during quiet and disturbed TIONS ‘WHEN’ AND FOR ‘HOW LONG’: periods. These observations are expected to A REALITY? augment our understanding of the equatorial plasma bubble phenomenon. R. Sridharan1, Mala S. Bagiya1, and Surendra 2 TYPE: ORAL Sunda DATE: 2012-03-13 – 08:45 1 Physical Research Laboratory, Ahmedabad, India GLOBAL S4 INDEX OBSERVED BY 2 Space Applications Centre, Ahmedabad, In- FORMOSAT-3/COSMIC dia

18 ISEA13 - 13th International Symposium on Equatorial Aeronomy

An operational forecasting of L band scin- plasma bubbles can exist up to 100 hours. It tillation is very vital for real time satellite based was concluded that there is enough time for the communication and navigation. Two of the plasma bubbles to survive and to be detected many fundamental questions viz., ‘when’ and (e.g., in minor species of ion composition in- for ‘how long’ the scintillation patches are likely side the bubble like He+) at the topside iono- to be present have been answered conclusively. sphere altitudes. (b) It was revealed that the A novel method based on GPS-TEC (GTEC) topside plasma bubbles can be easily detected data several hours before the actual event has as He+ density depletions during high/ maxi- been worked out. The close linkage between mal solar activity. The convenient conditions the perturbation features and the evolutionary for observations appear because the strong de- pattern of the scintillation enables us to fore- pleted in He+ density bubbles, reaching the cast ‘when’ and for ‘how long’ the L band scin- topside ionosphere, most well contrast with the tillations could occur, in addition to their occur- He+ density background layer very well de- rence pattern. The ‘first’ of its kind of results veloped in topside ionosphere during high so- take us one step closer towards the operational lar activity [ Wilford et al., JGR, 2003]. (c) forecasting of L band scintillations. He+ density depletions were considered in connection with equatorial F-region irregularities TYPE: ORAL (EFI), equatorial F-spread (ESF) and equato- DATE: 2012-03-13 – 09:15 rial plasma bubbles (EPB). Their longitudinal statistics, calculated for all seasons and both hemispheres (20?50?INVLAT), were compared HE+ DENSITY DEPLETIONS AS IN- with EFI statistics taken from AE-E [McClure DICATOR OF THE TOPSIDE IONO- et al., JGR, 1998], OGO-6 [Basu et al. RS, SPHERE PLASMA BUBBLES 1976], ROCSAT [Su et al., JGR, 2006] observations. ESF(RSF), EPB statistics taken from Sergey Filippov [Maruyama, Matuura, JGR, 1984; Watanabe, Oya, JGG, 1986] based on ISS-b and Hino- IZMIRAN, Pushkov Institute of Terrestrial tori data were also used for comparison. It Magnetism, Ionosphere and Radio Wave Prop- was revealed that the main statistical max- agation RAS, Troitsk, Russia ima of the equatorial F-region irregularities are well enough reflected in the statistical plots of He+ density depletions, considered as origi- the He+ density depletions of the both hemi- nating from equatorial plasma bubbles, were in- spheres. The best conformity was obtained for volved in this study. They are usually detected equinoxes, the worst one - for solstices, when in the topside ionosphere ( 1000 km) deeply the most dramatic insolation differences take inside the plasmasphere (L 1.3-3) [Sidorova, place in the different hemispheres. Hence, it ASR, 2004, 2007]. a) Since there are some was validated once again that He+ density de- questions about survival possibilities of the top- pletions may be considered as an indicator of side plasma bubbles, the characteristic times topside plasma bubble presence or as fossil bub- of the main processes, in which plasma bubble signatures. bles are involved, were compared. It was suggested that plasma bubbles are produced by TYPE: ORAL Rayleigh-Taylor instability at the bottomside of DATE: 2012-03-13 – 09:30 ionosphere and transported up to the topside ionosphere. It was found that it takes about 3-4 hours for plasma bubbles to reach the top- P1.01 CASE STUDIES OF SOME SPEC- side ionosphere altitudes. It was revealed that TACULAR JET STREAMS IN THE TRO- ambipolar diffusion transport is the most fast POSPHERE AND LOWER STRATO- (some minutes). The estimation of the Bohm SPHERE OVER TWO MAJOR STA- (cross-field) diffusion time shows that topside TIONS IN NIGERIA

19 ISEA13 - 13th International Symposium on Equatorial Aeronomy

M.A. Ayoola and G.O. Akinlade shows that the equinoctial FAIs coincided well with GPS scintillations and TEC fast deple- Obafemi Awolowo University, Ile-Ife, Nigeria tions, which are associated with the development of equatorial plasma bubbles (EPBs). Distinct variations in levels of jet streams However, for the June solstitial FAIs, some from troposphere into the lower stratosphere post-midnight FAI structures over Sanya may have been clearly revealed over two major originate from equatorial F region and then Nigerian stations; Lagos (Lat. 06o 32? N, extend to Sanya latitude along magnetic field Long. 03o 21?E) and Kano (lat.12o 03? lines, but the others could resemble the irregu- N, Long.08o 32? E) by an analysis of over larities of localized origin, not associated with 360 radiosonde/rawinsonde observations made the equatorial process. Both types of post- over the station. These jets cases range midnight FAIs during June solstice are not ac- from low-level jet, (LLJ) near the planetary companied by GPS scintillations and TEC de- boundary layer, to prominent ones at 650- pletions, but are associated with the occurrence 700hpa, 500hpa and 300hpa pressure levels. of spread-F. On the other hand, we present The heights of the jet cores range between 3km some measures of EIA asymmetry and pre- to18km in most of the period of occurrence.. reversal vertical drifts around sunset in the Chi- The troposphere is seen to be a significant layer nese longitude sector, and investigate their cor- in this study because 80% of the atmosphere’s respondence with the day-to-day variability of mass is located within it and almost all of what ionospheric plasma bubbles during equinox over we call “weather” occurs in the troposphere. Sanya. On the ten nights studied in the present The average position of jet stream and inten- investigation, it has been observed that the ge- sity varies with the seasons. omagnetic disturbances have a strong inhibition effect on the F region irregularities. TYPE: POSTER DATE: 2012-03-13 – 17:35 TYPE: POSTER DATE: 2012-03-13 – 17:35 P1.03 CHARACTERISTICS OF THE IONOSPHERIC F-REGION IRREGULAR- P1.04 ON THE RELATIONSHIP OF ITIES OVER SANYA MULTI-REFLECTED ECHOES TO

1 2 LARGE-SCALE WAVE STRUCTURE Guozhu Li and Baiqi Ning AND EQUATORIAL SPREAD F 1 Institute of Geology and Geophysics, Chinese Thu Trang Nguyen1, Roland Tsunoda2, and Academy of Sciences, China Mamoru Yamamoto3 2 Beijing National Observatory of Space Envi- ronment, Institute of Geology and Geophysics, 1 HCMC Institute of Physics, VAST, HCMC, Chinese Academy of Sciences, Beijing, China Vietnam 2 SRI International, Menlo Park, CA, USA Data from the continuous observations of 3 Research Institute for Sustainable Hu- ionospheric F region irregularities by a VHF co- manosphere, Kyoto University, Japan herent radar, an ionosonde and a GPS scintillation/TEC receiver over Sanya (18°N, 109°E, There is considerable interest in under- dip 13ºN) are analyzed. It is found that standing the day-to-day variability in occur- the F region 3-m scale ﬁeld aligned irregular- rence of plasma structure in the nighttime ities (FAIs) appeared frequently at post-sunset equatorial F layer, often referred to as equa- hours during equinox but initiated mostly at torial spread F (ESF). While there is wide ac- midnight/post-midnight in June solstice at so- ceptance of the notion that the vigor of the lar minimum. Comparison of FAIs with GPS post-sunset rise (PSSR) of equatorial F layer scintillations, TEC ﬂuctuations and spread-F is largely responsible for whether ESF occurs

20 ISEA13 - 13th International Symposium on Equatorial Aeronomy or not, there is mounting evidence that large- P1.05 IONOSONDE OBSERVATIONS OF scale wave structure (LSWS), which develops in SPREAD F IRREGULARITIES AT LOW the bottomside F layer prior to onset of ESF, LATITUDE PAMEUNGPEUK (INDONE- may also be playing a role. The role of LSWS SIA) DURING LOW SOLAR ACTIVITY involvement in ESF development has not received much attention because virtually all sen- Prayitno Abadi and Buldan Muslim sors in use (until recently) are not being used Space Science Center, Indonesian National In- to detect or describe LSWS. In an effort to de- stitute of Aeronautics and Space, Indonesia velop new methods for doing so, we have be- gun to search for features in equatorial iono- Spread F (SF) signatures on ionograms are grams that could be related to the presence manifestation of ionospheric irregularities in the of LSWS. Early indication is that the so-called F layer ionosphere. The basic mechanism of multi-reflected echoes (MREs) are an ionogram SF is associated with pre-reversal enhancement signature for LSWS [Tsunoda, 2009]. The (PRE) of the eastward electric field after sun- cause of MREs is believed to be an enhance- set. PRE indicates upward E × B plasma drifts ment of the ionospheric reflection coefficient, elevate the F layer sufficiently for spread F ini- which occurs when concave isodensity contours tiation. Nevertheless, PRE is not a more-direct associated with LSWS are situated over the precursor of spread F. Although PRE is associ- ionosonde. The results in this presentation ated with SF climatologically, our observational come from an ongoing study, whose objective evidence which indicate that SF is not always is to determine the properties of MREs and associated with PRE. By using ionosonde that their relationship to LSWS and ESF. The re- installed in Pameungpeuk, we investigated vir- sults to be presented include: (1) a description tual height (h’f) variations of F layer to indicate of how MREs are manifested in ionograms, (2) correlation between PRE and spread F occur- examples that show the relationship of MREs rences during 2009 (low solar activity). We to upwellings in LSWS, and (3) the occurrence found that spread F occurrences is highest rate frequency of MREs as a function of time of occurrences on March, and we found asymme- day, season, solar and magnetic activity. The try occurrences of spread F on equinox, spread results show that MREs are related to verti- F occurrences on February-March is higher than cal transport of local F-region plasma; the re- September-October. The primary results, most sults are consistent with the notion that plasma of spread F occurrences on Jan, Nov, and Dec seeding could be a consequence of atmospheric are well-correlated with PRE. On the other gravity waves and neutral-ion coupling in the hand, most of spread F occurrences on Apr, bottomside F layer. Data used for this study May, Jul and equinox months are negative cor- include ionograms from the Kwajalein Atoll, related with PRE. Marshall Islands, and total electron content (TEC) variations derived from the reception TYPE: POSTER (also at Kwajalein) of radio beacon transmis- DATE: 2012-03-13 – 17:35 sions from the equatorial-orbiting, Communi- cation/Navigation Outage Forecasting System (C/NOFS) satellite. The results are important P1.07 IONOSPHERIC STRONG RANGE because MREs can provide a continuous moni- SPREAD-F OBSERVED IN THE LOW tor of LSWS presence, which complements the LATITUDE STATION HAINAN beacon satellite measurements that are made Jiankui Shi only once every 90 minutes or so. Center for Space Science and Applied Research, Chinese Academy of Sciences, China TYPE: POSTER DATE: 2012-03-13 – 17:35 The spread-F is an important plasma irregularity in the ionosphere. Since a DPS-4

21 ISEA13 - 13th International Symposium on Equatorial Aeronomy digisonde was installed in the low latitude sta- Gadanki (13.45°N, 79.17°E, dip latitude 6.4°N), tion Hainan, China ( 19.4°N, 109.0°E geogr., Kolhapur(16.8°N, 74.2°E, dip latitude 10.6°N dip lat. 9°N ) in March 2002, ionograms were ) and Allahabad (25.3°N, 81.5°E, 16.24°N) recorded at 15-min intervals. The observed along with existing similar setup at Tirunelveli ionograms often show Strong range Spread-F (8.7oN, 77.8oE, dip latitude 0.60 N). Ampli- (SSF) in the ionosphere over Hainan station. tude scintillations on 251 MHz signal transmit- The SSF is similar to the range spread-F but the ted from geostationary satellite UFO2 (71.20 spread extends in frequency well beyond FoF2, E) and recorded at every 50 ms at all these sta- making the critical frequency of the F2 layer tions are utilized in the present work. Here we diﬃcult to be determined. Here, we statisti- present, ﬁrst results on the simultaneous scintil- cally study the SSF properties using the data lation observations recorded by this network of from 2002 to 2007. The results show that the VHF spaced receivers during January-October SSF mainly occurred in equinox months and 2011 to understand the latitudinal variability was more actively in high solar activity years. in the evolution of Equatorial Spread F (ESF) Occurrence of the SSF showed a small increase irregularities. Zonal plasma drift Vo, charac- with sunspot number (SSN) during equinoxes teristic velocity Vc, which is a measure of ran- and summer, and seemed insensitive to the dom changes in the irregularity characteristics SSN during winter. The peak occurrence of and maximum cross-correlation CI(x0,tm) be- the SSF were at 2100-2300 LT during high so- tween intensity variations of two receivers are lar activity years and at 2300-0100 LT during estimated for every 3 minute at each station. low solar activity years. The occurrence of the Quiet time monthly average pattern of zonal SSF was higher in the geomagnetic quiet pe- drift Vo and characteristic random velocity Vc riods than that in the geomagnetic disturbed are studied to get information about latitudinal periods. The SSF had a good correlation with variability of ESF irregularities. GPS L-band scintillations and we conclude that the SSF is associated with equatorial plasma TYPE: POSTER bubbles. DATE: 2012-03-13 – 17:35

TYPE: POSTER DATE: 2012-03-13 – 17:35 P1.09 IMPORTANCE OF IONOSPHERIC EQUATORIAL VHF SCINTILLATION IN THE INDIAN REGION TO STUDY SUN- P1.08 NEW NETWORK OF SPACED RE- EARTH INTERACTIONS CEIVER VHF SCINTILLATION EXPER- 1 1 IMENTS OVER INDIAN REGION: RE- Sridhar Banola , R. N. Maurya , and Harish 2 SULTS ON ESF IRREGULARITIES. Chandra 1 Diwakar Tiwari1, G. Surve1, C. K. Nayak1, Indian Institute of Geomagnetism, Navi B. Kakad1, S. Sripathi1, Amit K. Patra2, Mumbai, India 2 K. Jeeva1, K. U. Nair1, C. Selvaraj1, R. N. Physical Research Laboratory, Ahmedabad, Maurya1, P. Tiwari1, P T Patil1, R. Ghodpage1, India and Archana Bhattacharyya1 Plasma density irregularities in the iono- 1 Indian Institute of Geomagnetism, Navi sphere (associated with ESF, plasma bubbles Mumbai, India and Sporadic E layers) cause scintillations in 2 National Atmospheric Research Laboratory, various frequency ranges. VHF radio wave scin- Gadanki, India tillation technique is extensively used to study plasma density irregularities of sub-kilometre Network of spaced receivers recording VHF size . Eﬀects of magnetic and solar activity on scintillations have been established over equa- ionospheric irregularities are studied so as to torial and low latitude Indian stations at ascertain their role in the space weather of the

22 ISEA13 - 13th International Symposium on Equatorial Aeronomy near earth environment in space. Indian Insti- 4 Instituto Nacional de Pesquisas Espaciais - tute of Geomagnetism operated a ground net- INPE, Sao Jose dos Campos, SP, Brazil work of 13 stations monitoring amplitude scin- 5 Department of Electrical, Electronic and tillations on 244/251 MHz (FLEETSAT 73°E) Systems Engineering, Universiti Kebangsaan signals in India for more than a decade un- Malaysia (UKM), Malaysia; Institute of der AICPITS. At present VHF scintillation is Space Science, Universiti Kebangsaan Malaysia being recorded at Mumbai by monitoring 251 (UKM), Malaysia MHz signal transmitted by geostationary satellite UFO2(71.2? E), sampling at 20 Hz. VHF Rocket borne measurements of electron scintillation was monitored at Mumbai during temperature involve much more than a mere CAWSES Campaigns 2006 and 2008 During complement to the overwhelming amount of campaign 2006 (low sunspot period) occur- data provided by ground-based instruments and rence of daytime scintillations was higher than satellites. They are the most suitable technique the nighttime scintillations. This could be due to perform direct measurements of phenom- to the fact that during low sunspot years occur- ena that evolve vertically, as well as to pro- rence of spread-F is limited to a narrow latitude vide vertical profiles of parameters in the at- region near the dip equator. To study solar cy- mosphere/ionosphere system over a range of cle association of scintillations, long series of si- altitude currently inaccessible to both balloons multaneous amplitude scintillation data for pe- and satellites. A rocket experiment carried riod Jan 1989 to Dec 2000 at different locations out on December 18th, 1995 at 21:17 h (LT) are utilized. Nighttime scintillation occurrence over the equatorial station Alcântara (2.31oS; is solar activity dependent Though equatorial 44.4oW), Brazil, measured both electron den- scintillations are inhibited due to the magnetic sity and temperature. These measurements re- activity in general, there are cases when strong vealed, just before the development of plasma scintillations result during magnetic storms es- bubbles, a region of large electron temperature pecially in the post midnight period. below the base of the F-layer. Once the bubbles are developed these large values of temperature TYPE: POSTER drop significantly while relatively large temper- DATE: 2012-03-13 – 17:35 atures can now be preferentially observed at the top inside of the bubbles. This phenomenon is examined in the light of results provided by the P1.10 ELECTRON TEMPERATURE EN- Global Self-Consistent Model of the Thermo- HANCEMENTS IN NIGHTTIME EQUA- sphere, Ionosphere and Protonosphere (GSM TORIAL IONOSPHERE UNDER THE TIP) developed by WD IZMIRAN, as well as OCCURRENCE OF PLASMA BUBBLES an alternative 2D numerical simulation that re- produces the growth of an instability and the Francisco Carlos De Meneses1, Maxim evolution of energy inside a bubble. The pre- Klimenko2, Vladimir Klimenko2, Esfhan Alam vious results of this analysis suggest that the Kherani3, Polinaya Muralikrishna4, Alina Marie enhancements observed below the base of the Hasbi5, and Jiyao Xu1 F-region and at the top side of bubbles seem to be a geophysical phenomena. Furthermore, 1 State Key Laboratory of Space Weather, Cen- it also suggest that the intra-bubble tempera- ter for Space Science and Applied Research ture enhancements are formed due to the con- (CSSAR), Chinese Academy of Sciences, Bei- vection of hot fluid from bottomside to higher jing, China altitude and due to the large divergence in the 2 West Department of Pushkov Institute of ion velocity near the upper boundary of bubble. Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS, Kaliningrad, Russia TYPE: POSTER 3 Institut de Physique du Globe de Paris, DATE: 2012-03-13 – 17:35 CNRS, Paris, France

23 ISEA13 - 13th International Symposium on Equatorial Aeronomy

P1.11 VARIABILITIES OF IONO- features at KNC and RPMC. The summer SPHERIC SCINTILLATIONS AROUND solstitial scintillations in the premidnight pe- EQUATORIAL IONIZATION ANOMALY riod are also observed to exhibit reverse spa- CREST OF THE INDIAN ZONE tial feature compared to equinoctial months. Scintillations occur earlier at KNC with higher Shyamal Kumar Chakraborty, Satarupa Chat- fade rate, strength, duration, greater spectral terjee, Sourav Mazumdar, and Rajkumar Hajra slope of power spectra than those at RPMC. No Fresnel oscillations are observed in spectral Raja Peary Mohan College, India features. Mid-latitude type possibly of E-layer irregularity may be the origin of scintillation. Results of scintillation observations at Cases are observed when scintillations are de- VHF (250 MHz) from three locations tected at RPMC in the postsunset hours baring (Bokkhali/BOK (21.58°N, 88.24°E), Raja at KNC with distinct signatures of Fresnel os- Peary Mohan College/RPMC (22.66°N, cillation implying that thin F-layer irregularity 88.39°E), Krishnath College/KNC (24.1°N, may be the possible sources. Sometimes scin- 88.32°E)) around the equatorial ionization tillation starts at late premidnight hours con- anomaly (EIA) crest will be presented. The tinued up to predawn hours with comparatively study will be augmented by observations at higher fade rate, duration, depth of scintillation GPS, GLONASS and SBAS frequencies in the at RPMC than at KNC. Power spectral analy- context of studying temporal and spatial vari- sis reveals BSS type irregularities. The results ability pattern of amplitude scintillation around accrued form a useful database for modeling the most vulnerable zone of the globe. In the studies of scintillation around the equatorial equinoctial months distinct temporal and spa- anomaly crest. tial variability features are reflected in the occurrence characteristics of VHF scintillation. TYPE: POSTER The postsunset scintillations are found to initi- DATE: 2012-03-13 – 17:35 ate first at BOK followed by RPMC and KNC. The highest fading rate, depth, duration, spectral slope are recorded at BOK with the gradual P1.12 ON THE EVOLUTION OF decrease of the same at RPMC and KNC re- MEDIUM (HUNDRED’S OF M) AND spectively. Scintillations are also recorded in SMALL (FEW M) SCALE ESF IRREG- three SBAS satellites, GLONASS and GPS ULARITIES: A NEW LOOK THROUGH tracks and they are found to be associated GPS WINDOW with TEC depletions/bite-outs. The plasma bubble associated irregularities generated near Mala S. Bagiya and R. Sridharan the magnetic equator and mapping down along the field line may trigger the scintillation ac- Physical Research Laboratory, Ahmedabad, In- tivities around the three locations with associ- dia ated temporal and spatial variability features. It is ascertained by the ionosonde data from The evolutionary pattern of different scale the equatorial location. Scintillation along the sizes of plasma density irregularities associ- tracks of various GPS, GLONASS satellites ated with Equatorial Spread-F (ESF) have been may give an approximate idea of extent of ir- studied using GPS-TEC (GTEC) data along regularity belt along with its temporal evolution with the basic data on the F region heights feature. Compared to the equinoctial months, in the post sunset hours. It has been seen that scintillation in summer solstitial months ex- the evolutionary pattern is very closely related hibits certain distinctive features which are to the fluctuations in the GTEC and also to reflected in occurrence time, fade rate, depth, the ion-neutral collision frequency. The back- and duration of scintillation. Nature of sum- ground thermospheric conditions that affect mer daytime scintillation exhibits remarkable the growth of the plasma instability through

24 ISEA13 - 13th International Symposium on Equatorial Aeronomy ion-neutral collision frequency (?in) are esti- from seeded parcels grown along high conduc- mated using the F region base height (h’F) and tivity magnetic field channels. Which is nowa- the representative scale height of the neutral days confirmed: plane Internal Gravity Waves atmosphere and are presented by a growth fac- (IGW), from the lower atmosphere traveling to tor (G). The variations in GTEC with respect upper thermosphere, with a dominant forcing to GTEC is derived and considered to repre- role, could be the seeding for such dense elec- sent the seed perturbations for the generation tron anisotropies. Then fully developed as re- of ESF irregularities. This perturbation fac- gional extent patches and propelled by the ion- tor (P) along with the growth factor has been drift travel resembling forced westerly propa- shown to reproduce the complete evolutionary gating Plane Waves. After kindly invitation pattern. The investigation demonstrates that from the ISEA-13 Organizing Committee the if one gets a handle on above two factors, one author has learned from the web, that this fa- could foresee the evolutionary pattern of the vorite scientific topic is still as enigmatic, as medium and small scale irregularities associated half century ago!!! Therefore gladly moved with the ESF which requires immediate atten- to dig for and fortunately got some that time tion from the point of view of satellite based data relics (1965-1966, Polar satellite passes). communication and navigation. These re-analyzed, will be presented. Due to elements separation, ?=10.5Km and the radio TYPE: POSTER wavelength ?=2.2m at 136MHz, the scenario DATE: 2012-03-13 – 17:35 was found amenable for a simple ray-tracing analysis Anecdotically: late on the 90s, after years using IGW on Solarterrestrial and mag- P1.14 PLANE WAVES FORCING ON netosphere substorm phenomena, as visitor sci- EQUATORIAL “F-SPREAD”, EARTH- entist at GSFC NASA, the author moved back SUN, UNIVERSE PHENOMENA . . . AND Lima-Peru, working at a copper smelter, has ON “UPCASTING” learned about most salient kind of “quantum effects at macro-scale”: The way to cast bar feedstock’s to fabricate wire, is by wavy pulling- G. Tisnado up of the bar from the melt (continuously will never work!!!) Within this “up-casting” tech- TECNOFIL S.A., Lima, Perú nology, the sharper wave front pull, the plenty and better the produce! Obviously the physical Tracking satellites at Minitrack Station, model chosen was: “forced plane IGW’s propa- Ancon Lima-Peru on the 60s, conspicuous gate into the critical solid-liquidus zone. Finally East-West-Only trajectory distortions occurred, substantiating above views: “severe geomag- mostly during past-equinox evenings. These netic anisotropic undulations, near the F max were associated with geomagnetic aligned elec- layer”, ROJ Spread-F vs Ancon Satellite Scintil- tron density irregularities at F-region Equatorial lations, data sets from concurrent experiments Ionosphere. Taking advantage of a unique con- done, along with resent MODIS satellite obser- figuration given by: (i) Polar Satellite passes vations of IGW over Northern Peru, will also be (ii) precise Minitrack radio interferometry at presented. Pertinent Physical-Mathematics ex- 136MHz, (iii) local Geomagnetic Field: zero plaining the IGW salient role in the addressed dip due N-S, and (iv) the near-equinox Equa- henomena will be sketched. torial Ionosphere dynamics, the author had collected pertinent data sets, study irregular- TYPE: POSTER ities dominant scale morphology and charac- DATE: 2012-03-13 – 17:35 terize those as: “Sharply N-S oriented quasi- periodic vertical gradient crests of electron distribution near F max”. Physically it was as- P1.15 MORPHOLOGY OF PLASMA TEC sumed, vertical plane structures could result DEPLETIONS OVER SOUTH AMERICA

25 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Cesar Valladares 2 Virginia Polytechnic Institute and State Uni- versity, Blacksburg, VA, USA Boston College, MA, USA 3 University of Alaska Fairbanks, AK, USA 4 Thayer School of Engineering at Dartmouth, This paper presents regional plots of TEC Hanover, NH, USA depletions derived from GPS observations over the South American continent with a cover- We present extended scatter observations age of over 45° longitude (i.e., 35? to 80° that are associated with the nighttime iono- W). A new numerical algorithm has been de- spheric mid-latitude trough. Using data from veloped to automatically detect TEC bite-outs five mid-latitude SuperDARN HF radar sites, that are produced by the transit of equatorial including two radars with greater than 4 years plasma bubbles. This algorithm was applied of observations, we are able to compare with to TEC values measured by the Low Latitude trough observations derived from electron den- Ionospheric Sensor Network (LISN) and by re- sity occultation measurements obtained from ceivers that belong to 4 other networks that the COSMIC suite of satellite. We examine the exist in South America. The general charac- scatter characteristics with respect to trough teristics of the TEC depletions are provided depth and location. Additionally, we examine along with their temporal length, local time longitudinal differences between sites and cli- distribution and depletion depth. The regional matology as a function of seasons and local day-to-day and seasonal variability of the TEC time. depletions are also presented for three years TYPE: POSTER of low solar activity: 2008, 2009 and 2010. DATE: 2012-03-13 – 17:35 The regional day-to-day variability of TEC depletions is highly dynamic, but their seasonal distributions follow the longitudinal character- P1.18 REFINING MEASUREMENTS OF istics of plasma bubbles presented by other THE SPREAD IN ASPECT ANGLES OF authors. During the equinoxes, TEC deple- RADAR SCATTER FROM EQUATORIAL tions are mainly observed on the west coast ELECTROJET IRREGULARITIES of South America, and during the December Wesley E. Swartz1, Donald T. Farley1, Jorge solstice they mostly occur on the east side of Chau2, Henry Pinedo3, and Karim Kuyeng2 the continent. However, in all seasons we observe days when depletions extend all over the 1 School of Electrical and Computer Engineer- continent. These new results are placed in the ing, Cornell University, Ithaca, NY, USA context of theories of plasma bubble seeding. 2 Radio Observatorio de Jicamarca, Instituto Geofísico del Perú, Lima, Perú TYPE: POSTER 3 University of Tromsø, Norway DATE: 2012-03-13 – 17:35 We report new measurements of the spread in aspect angles within the equatorial electro- P1.16 EXTENDED OBSERVATIONS OF jet above the Jicamarca Observatory. This up- DECAMETER SCATTER ASSOCIATED dates the work of Lu et al. [2008] with more WITH THE MID-LATITUDE IONO- and longer baselines so that the shape of the SPHERIC TROUGH distribution can be better defined. The work of Kudeki and Farley [1989] used just one base Elsayed Talaat1, Ethan Miller1, J. Michael line, while Lu et al. [2008] used 6. We have Ruohoniemi2, William Bristow3, Raymond now used 10 baselines with the longest being Greenwald2, and Simon Shepherd4 a factor of 1.9 longer than used previously. We find that the coherence as a function of 1 Applied Physics Laboratory, John Hopkins k D kDθ (where D is a vector base- · ≈ RMS University, MD, USA line, k is the incoming wave vector, and θRMS

26 ISEA13 - 13th International Symposium on Equatorial Aeronomy is the complement of the averaged angles be- 20.44W dip) -Brazilian region, Jicamarca (12S, tween k and D) nicely follows Gaussian shapes 283.1E, 0.3E dip) - Peruvian region and Christ- down to small coherence values at the longest mas Island (2N, 202.6E, 8.55E dip) - Central baselines for typical values of θRMS for many Pacific region, are important for space weather of the heights and Doppler shifts of data from program/forecasting/nowcasting and improv- within the electrojet. This confirms our pre- ing scintillation warning models. These param- vious assumptions for single baseline analysis eters show linear correlation with solar flux in- that the shape is indeed Gaussian. dex (F10.7cm), as well seasonal and magnetic declination angle variation. In this talk we show Kudeki, E., and D. T. Farley, Aspect sensitivity the statistical analysis of the plume parame- of equatorial electrojet irregularities and theo- ters, collected from three different longitudinal retical implications, J. Geophys. Res., 94, 426- sectors, the fit correlation with F10.7cm and 434, 1989. Kp indexes in order to develop an spread-F for- Lu, Fei, D. T. Farley, and W. E. Swartz, mation empirical model based on small scale Spread in aspect angles of equatorial E region irregularities. Onset altitude/time of bottom- irregularities, J. Geophys. Res., 113, A11309, type spread F present a linear regression with doi:10.1029/2008JA013018. the solar flux index (F10.7cm ), in agreement with Chapagain et al.(2009), with differences TYPE: POSTER in time/altitude from seasonal and longitudi- DATE: 2012-03-13 – 17:35 nal basis.Peak altitude of topside plumes show high saturation when going from low to high P1.19 STATISTICAL ANALYSIS OF solar flux activity. VHF RADAR PLUME PARAMETERS TYPE: POSTER AT THREE LONGITUDINAL SECTORS DATE: 2012-03-13 – 17:35 (SãO LUíS, JICAMARCA AND CHRIST- MAS ISLAND).

Ricardo Cueva1, Eurico De Paula1, and Esfhan P1.21 CLIMATOLOGICAL STUDY OF Alam Kherani2 THE DAYTIME OCCURRENCE OF THE 3-METER EEJ PLASMA IRREGULAR- 1 Instituto Nacional de Pesquisas Espaciais - ITIES OBSERVED OVER THE JICA- INPE, Sao Jose dos Campos, SP, Brazil MARCA CLOSE TO THE SOLAR MIN- 2 Institut de Physique du Globe de Paris, IMUM (2007 AND 2008) CNRS, Paris, France Lais Maria Guizelli, Clezio Marcos De Nardin, ESF are manifestation of ionospheric inter- Juliano Moro, and Laysa Cristina Araújo Re- change instabilities in the nighttime equatorial sende F region. These instabilities generate plasma density irregularities with scale sizes ranging Instituto Nacional de Pesquisas Espaciais - from centimeters to thousands of kilometers. INPE, Sao Jose dos Campos, SP, Brazil The irregularities can be detected by coherent and incoherent scatter radars, in situ space We have developed algorithms for conduct- probes, radio propagation and scintillation ex- ing a seasonal statistical study of the occur- periments, and airglow detectors in addition to rence of plasma irregularities type 1 (due to ionosondes. The plume parameters here pre- modiﬁed two-stream instability) and type 2 sented are onset altitude and time of bottom- (gradient-drift instability) as function of height type and plume, as well as the peak altitude and local time, in the Peruvian sector cover- of the topside plumes. Plume parameters pro- ing two years of data (2007 and 2008), close cessed from VHF Radars collected from equato- to the solar minimum. This study is performed rial stations located at São Luís (2.59S, 315.8E, based on radar measurements carried out at the

27 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Jicamarca Radio Observatory (JRO), located exists a definite seasonal and solar flux vari- in Lima - Peru (11.57°S, 76.52°W, dip: 2°N), ation as seen in the vertical drift velocity as under the magnetic equator. The statistical well as ion density at ROCSAT-1 altitude over analysis runs over daily Range Time Intensity Indian region which in turn reflected in the oc- (RTI) maps obtained with the radar operat- currence of scintillations. In addition, these ob- ing in the Jicamarca Unattended Long-term In- servations also suggest that vertical drift ve- vestigations of the Ionosphere and Atmosphere locity rapidly enhanced in the evening hours (JULIA) mode. Our results revealed relevant during equinox followed by winter and sum- features of the diurnal variation of the plasma mer seasons, respectively. The seasonal and irregularities embedded in the equatorial elec- latitudinal variations of ion density show the trojet, such as a more often presence of the development of Equatorial Ionization Anomaly 3-m irregularities during equinox and a descent (EIA) which is found to vary with solar flux of the scattering profile in the morning hours, and season. The EIA development is visible followed by its rising in the afternoon. clearly during equinox followed by winter and show signature of solar flux variations. How- TYPE: POSTER ever, latitudinal extent of EIA has been found DATE: 2012-03-13 – 17:35 to be suppressed during summer seasons. In addition, as solar flux decreases, strength of EIA also decreases, but rather slowly. The sea- P1.23 SEASONAL AND SOLAR FLUX sonal variations of EIA development and verti- VARIATION OF IONOSPHERIC F- cal drift velocity are highly correlated with EEJ REGION ION DENSITY AND DRIFTS AS strength during equinox followed by winter and OBSERVED BY ROCSAT-1 AND THEIR summer seasons, respectively. As solar flux de- COMPARISON WITH GROUND BASED creases, vertical drift velocity as well as EIA EEJ STRENGTH AND VHF SCINTILLA- development also decrease over Indian region TIONS OVER INDIAN REGION and hence occurrence of ground scintillations is reduced. While these observations are in accor- Samireddipalle Sripathi1, S. Tulasi Ram2, Amit dance with earlier ionosonde observations over K. Patra3, and Bharati Kakad1 Indian region, we present new results showing seasonal and solar flux variations of drift veloc- 1 Indian Institute of Geomagnetism, Navi ity using ROCSAT-1 and compare these vari- Mumbai, India ations to the EEJ strength and their influence 2 Equatorial Geophysical Research Laboratory, on the occurrence of scintillations/Equatorial Indian Institute of Geomagnetism, India Spread F (ESF) irregularities over Indian re- 3 National Atmospheric Research Laboratory, gion. Gadanki, India TYPE: POSTER In this paper, we present the quite-time DATE: 2012-03-13 – 17:35 variation of solar flux, seasonal variation of vertical drift velocity and ion density at an altitude of 600 km as obtained by ROCSAT-1 over In- P1.26 INTERMEDIATE SCALE LENGTH dian region during the years 1999-2004, and ESF IRREGULARITY SPECTRUM AND their comparison with ground based (a) Equa- ASSOCIATED ELECTRIC FIELD FLUC- torial Electrojet (EEJ) as obtained by ground- TUATIONS based geomagnetic field variations, (b) spaced receivers VHF scintillations and (c) small scale Archana Bhattacharyya, Diwakar Tiwari, and irregularities obtained using VHF radar to study S. Sripathi the background conditions under which the ionospheric irregularities/scintillations are ob- Indian Institute of Geomagnetism, Navi Mum- served. These observations suggest that there bai, India

28 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Ionospheric scintillation measurements and DATE: 2012-03-13 – 17:35 ionosonde observations at an equatorial station are used to study the influence of ambient conditions on the simultaneous evolution P1.27 MERIDIONAL ELECTRIC FIELD of the intermediate scale length ( 100m – 1 MEASUREMENTS OF LAYER-TYPE km) ESF irregularity spectrum as well as the AND BLOB-TYPE PLASMA STRUC- perturbation electric field associated with the TURES IN MID-LATITUDE SPORADIC Generalized Rayleigh – Taylor (GRT) instabil- E REGION: PLAUSIBLE GENERATION ity. Amplitude scintillations on a 251 MHz sig- MECHANISMS nal transmitted from a geostationary satellite and recorded by two receivers spaced along a Yen Hsyang Chu magnetic east-west baseline at an equatorial station are used to estimate the zonal drift of Institute of Space Science, National Central the ground scintillation pattern, and the ’ran- University, Taiwan dom velocity’, which may be considered to be It has long been known from interferometer a proxy for the perturbation electric field as- measurement that spatial structures of echoing sociated with the GRT instability. For weak regions of 3-m field-aligned irregularities (FAIs) amplitude scintillations with S4 index ? 0.5 in Es region can be categorized into layer- and , where S4 index is the standard deviation of blob-types. The layer-type structure is charac- normalized intensity fluctuations, the spectral terized by wide extent in horizontal and nar- index of a power-law type of spectrum of am- row thickness in vertical directions, and the plitude scintillations for frequencies higher than blob-type structure is in quasi-isotropic shape. the Fresnel frequency yields an estimate of the A method is proposed to measure meridional spectral index of a power-law irregularity spec- electric fields inside these two type echo struc- trum. In general it is found that for a scin- tures observed by the Chung-Li VHF radar. On tillation event, the ‘random velocity’ tends to the basis of the radar data collected more than decrease as the irregularity spectrum steepens. one year, we find that the meridional electric This would indicate that as the electric field field of the layer-type structure is very different fluctuations associated with the irregularities from that of the blob-type structure. Statisti- decrease, the shorter scale length irregularities cal results indicate that the former is in average also decay, which results in a steeper spectrum. about 1-2 mV/m that points in the direction in Presumably the spectrum of electric field fluc- compliance with that predicted by neutral wind tuations also steepens, although no such in- shear theory. However, the electric field inside formation is available in this study. However, the blob-type structure is very weak with irreg- since the development of the GRT instability ular pointing direction. It is believed that the takes place in a dynamic background the man- plausible mechanisms responsible for the forma- ner in which the two physical processes are in- tions of the layer-type and clump-type plasma terlinked varies from one scintillation event to structures are, respectively, very likely the con- another. Here the influence of the dynamics of vergence of neutral wind shear and the propa- the post-sunset background equatorial F layer gating gravity wave. on the behavior of the irregularity spectrum and electric field fluctuations is explored. TYPE: POSTER DATE: 2012-03-13 – 17:35 TYPE: POSTER

29 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 2

E AND F REGION COUPLING (LOW AND MID LATITUDE COUPLING)

Understanding the coupling between the E and F region at low and midlatitudes is important to elucidate the physics behind several processes occurring there. This coupling involves electromagnetic forcing effects between the regions connected by the geomagnetic field. In addition to local coupling, effects from the conjugate hemisphere seem to play an important role in the overall behavior of the processes observed.

This session solicits contributions related to coupling studies between the E and F region. Con- tributions focusing on multi-instrument observations, computer simulation and theoretical studies, ionospheric irregularities, wave phenomena, and eﬀects of neutral atmosphere processes are encouraged.

Conveners: M. Yamamoto, J. Urbina, and C. Martinis

30 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - GPS OBSERVATIONS OF the nighttime MSTID occurrence could be at- MEDIUM-SCALE TRAVELING IONO- tributed to those of the Es layer occurrence SPHERIC DISTURBANCES OVER EU- rate. However, the seasonal variation of the ROPE nighttime MSTID occurrence over Europe is not consistent with this scenario. We specu- Yuichi Otsuka1, Shinta Nakagawa2, Michi late that the nighttime MSTID occurrence is Nishioka3, and Kazuo Shiokawa1 not controlled by the Es layer occurrence alone and that inhomogeneity of Es layer may be 1 Solar-Terrestrial Environment Laboratory, needed for the MSTID occurrence. Nagoya University, Japan 2 Graduate School of Engineering, Nagoya Uni- TYPE: ORAL versity, Japan DATE: 2012-03-16 – 08:00 3 National Institute of Information and Com- munications Technology, Japan INVITED - NUMERICAL MODELING Two-dimensional structures of medium- OF MEDIUM-SCALE TRAVELING IONO- scale traveling ionospheric disturbances SPHERIC DISTURBANCES (MSTIDS) (MSTIDs) over Europe have been revealed SEEDED BY SPORADIC-E LAYERS by using maps of the total electron content (TEC) obtained from more than 800 GPS re- Tatsuhiro Yokoyama ceivers of the European GPS receiver networks. From statistical analysis of the TEC maps, we Research Institute for Sustainable Hu- have found that the observed MSTIDs can be manosphere, Kyoto University, Japan categorized into two groups: daytime MSTID and nighttime MSTID. The daytime MSTID Plasma density structures and associated ir- frequently occurs in winter. Its maximum oc- regularities in the nighttime midlatitude iono- currence rate in monthly and hourly bin exceeds sphere are frequently observed as frontal struc- 70% at lower latitudes in Europe whereas it is tures elongated from northwest to southeast approximately 45% at higher latitudes.?Since (NW-SE) in the northern hemisphere, also most of the daytime MSTIDs propagate south- known as medium-scale traveling ionospheric ward, we speculate that they could be caused disturbances (MSTIDs). The MSTIDs and the by atmospheric gravity waves in the thermo- coupling process between the E and F regions sphere. The nighttime MSTIDs also frequently are studied with a three-dimensional numeri- occur in winter but most of them propagate cal model which can simulate two instability southwestward, in a direction consistent with mechanisms: Perkins instability in the F region the theory that polarization electric ﬁelds play and sporadic-E (Es)-layer instability in the E an important role in the generation of night- region. The fastest growth of the coupled in- time MSTIDs. The nighttime MSTID occur- stability occurs when the unstable conditions rence rate shows distinct latitudinal depen- on NW-SE perturbation are satisﬁed in both dence:?The maximum of the occurrence rate regions. The meridional component of a ro- in monthly and hourly bin is approximately tational wind shear blows an existing Es layer 50% at lower latitudes in Europe, whereas southward, and the F-region structure follows the nighttime MSTID was rarely observed at the E-region drift velocity. It has been con- higher latitudes. We have also compared the cluded that (1) the Es-layer instability plays a MSTID occurrence rate over Europe with that major role in seeding NW-SE structure in the in other regions and discussed the longitudinal F region, and the Perkins instability is required dependence of the nighttime MSTID occur- to amplify its perturbation, (2) the rotational rence rate along with the E- and F-region cou- wind shear in the E region produces southwest- pling processes. Previous studies suggest that ward phase propagation of the NW-SE struc- the longitudinal and seasonal dependencies of ture in both the E and F regions, and (3) the

31 ISEA13 - 13th International Symposium on Equatorial Aeronomy coupling process has a significant effect on the TYPE: ORAL scale of the Es-layer perturbation rather than DATE: 2012-03-16 – 08:40 the growth rate of the Es-layer instability. Re- cently, a new midlatitude ionosphere electrodynamics coupling model (MIECO) has been de- MSTIDS FROM HIGH TO LOW LATI- veloped which can model the coupling process TUDES between the E and F regions with dipole mag- Ethan Miller1, Elsayed Talaat1, Hyosub Kil1, netic field lines. Using the new model, MSTID Jonathan J. Makela2, and Larry Paxton1 structure is reproduced from random perturbation on an Es layer in a wide latitudinal range. 1 Applied Physics Laboratory, John Hopkins A typical wavelength of 150 km, larger ampli- University, MD, USA tude, and smaller MSTID’s tilt angles at lower 2 University of Illinois at Urbana-Champaign, latitudes are consistent with observations. It Urbana, IL USA is shown that the polarization process in the E region driven by neutral winds is essentially Nighttime medium-scale traveling iono- important for the full development of MSTIDs spheric disturbances (MSTIDs) are a common as well as the seeding of NW-SE perturbation feature of the middle and lower latitude iono- in the F region. With a little modification of sphere. These raised band structures propagate the coordinate system, the model is being ex- oblique to the magnetic meridian toward the panded to the equatorial region, which could equator and appear at magnetically conjugate be applied to the coupling between the equa- locations. Several theories exist to explain the torial and low-latitude ionospheres in terms of development and evolution of MSTIDs includ- the seeding of equatorial plasma bubbles. ing the often-cited Perkins instability, as well as ion-neutral coupling, and coupled E-F region TYPE: ORAL instabilities. We test these theories by fusing DATE: 2012-03-16 – 08:20 observations from radar and optical data sets to highlight relevant aspects of each.

MECHANISMS FOR E-F COUPLING TYPE: ORAL AND THEIR MANIFESTATION DATE: 2012-03-16 – 08:55 Russell Cosgrove VARIATIONS OF THE ES LAYER SRI International, Menlo Park, CA, USA PARAMETERS OVER EUROPE AND In this talk I will broadly review the main ASIAN REGION physical mechanisms and constraints thought Iurii Cherniak1, Jurij Nina Korenkov2, Vladimir to be involved in midlatitude E-F coupled phe- Leschenko1, and Irina Zakharenkova1 nomena, and discuss some measurements and criteria that might allow identiﬁcation of the 1 West Department of IZMIRAN, Kaliningrad, salient mechanisms in a particular case. The Russia discussion will involve mechanisms for polariz- 2 West Department of Pushkov Institute of ing sporadic E layers, eﬀectiveness of F region Terrestrial Magnetism, Ionosphere and Radio polarization, scale sizes for gravity waves in the Wave Propagation RAS, Kaliningrad, Russia E and F regions, mechanisms for modulating the F layer altitude, typical conductance ratios The information about statistical charac- and the E-F coupled electric circuit. As an ex- teristics of sporadic Es layer is necessary for ample to organize the discussion, the rocket the ionospheric dynamics study and for radio and radar study of Earle et al. [2010] will be applications. In this study we analyzed sea- reviewed with respect to the evidence for E-F sonal variations of foEs and probability of the coupling that it provides. layer’s appearance during period of low solar

32 ISEA13 - 13th International Symposium on Equatorial Aeronomy activity years 2008-2009 over midlatitudes of B. Kakad, S. Sripathi, and Archana Bhat- central Europe and Japan. This study is based tacharyya on the data of Kaliningrad ionosonde (54,6N; 20E) and Wakkanai and Kokobunji ionosondes Indian Institute of Geomagnetism, Navi Mum- in Japan. For each stations there was calcu- bai, India lated the monthly median and seasonal median diurnal variations. Additionally it was calcu- In the paper we present the observation of lated the average probability of Es layer appear- Ionospheric F3 layer Occurrence over equatorial ance. The Es layer with probability more than station Tirunelveli (77.8° E, 8.7° N, dip lat. 0.7° 30% was appeared from 08 to 17 LT in winter. N) under extremely prolonged low solar activity This time limit was practically coincided with period during 2007-2009. In this study statis- sunrise and sunset in winter. At night time Es tical analysis of the occurrence of the F3 layer layer practically did not appear. For summer observed over the equatorial station Tirunelveli season the Es probability is rather high at night is also presented. It is noticed that Occurrence time and can reach about 40% for Kaliningrad of F3 layer is maximum in the morning-noon ionospheric station. At day-time the probabil- period (09–11 hours IST) and also in the after- ity of Es layer appearance was about 80%. It noon hours with longer duration during sum- was carried out the comparison average val- mer solstice months of the year 2008 and 2009. ues of foEs with Migulin’s Es layer empirical Percentage occurrence of F3 layer has increas- model. It was revealed rather good agreement ing trend from the year 2007 to 2009 and solar with model for daytime in winter season and activity was minimum during 2009, confirming significant scattering of experimental data for the model predictions of Balan et al. (1998) other periods. Additionally we calculated the that the layer occurrence increases as the so- correlation dependences between Es probability lar activity decreases.foF3 varied from 3.5 to and foEs and stratosphere temperature changes 9.5 MHz and highest foF3 was observed during and have find the increasing of Es probability equinoctial month of March 2007 and minimum and diurnal values of foEs. We acknowledge in the winter month of February during 2009. the National Institute of Information and Com- Height of the F3 –layer corresponding to max- munications Technology (NICT) in Japan for imum foF3 for a given day varied from 300 to providing ionosonde data. 900 km and monthly maximum and minimum mean were observed during winter month of TYPE: ORAL October 2008 and November 2009 respectively. DATE: 2012-03-16 – 09:10 Duration of the F3 layer appearance varies from few minutes (15 minutes) to 4 hours and higher duration is observed during summer months. OCCURRENCE OF IONOSPHERIC F3 Few cases of F3 layer occurrence and its asso- LAYER OVER EQUATORIAL STATION ciation with Electrojet strength (?H Peak) are TIRUNELVELI UNDER EXTREMELY also presented. PROLONGED LOW SOLAR ACTIVITY DURING 2007-2009. TYPE: ORAL DATE: 2012-03-16 – 09:25 C. K. Nayak, Diwakar Tiwari, K. Emperumal,

33 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 3

WAVE PROPAGATION BETWEEN LOW/MIDDLE ATMOSPHERE AND IONOSPHERE

This session will focus on the main atmospheric waves such as acoustic-gravity waves, solar tides, planetary waves, Kelvin waves, etc. that primarily originate in the lower atmosphere, and on their transmission into the upper atmosphere.

The session will address both theoretical and empirical recent results concerning the transfer of momentum and energy by internal atmospheric waves, breaking and dissipation in the MLT region, wave-wave and wave-mean ﬂow interaction, chemical and dynamical coupling processes, and the MLT response to equatorial oscillations such as QBO and SAO. Contributions are particularly sought that focus on MLT wave seeding (wave penetration and secondary wave generation) of ionospheric disturbances and longitudinal structures and the dependence of wave coupling processes on the solar and geomagnetic activity. As it is widely recognized that numerical simulations driven by integrated ground-based and satellite observations are a powerful tool for quantitatively understanding the complex atmosphere-ionosphere system, and that they are a vital means for predicting the wave coupling processes, such results are most welcome. The main objective of this session is to provide the next opportunity for the international research community to review the progress made so far and suggest some future directions, particularly in studying the role of waves in atmosphere-ionosphere coupling.

Conveners: L. Goncharenko, D. Pancheva, and D. Scipion

34 ISEA13 - 13th International Symposium on Equatorial Aeronomy

SOLAR CYCLE EFFECTS IN THE IONO- groundbased total electron content (TEC) al- SPHERE: THE RELATIVE CONTRIBU- low us to investigate the interplay between the TION OF SOLAR VARIABILITY AND neutral, plasma, and background fields. LOWER ATMOSPHERE DRIVING We investigate analyses using empirical or- Elsayed Talaat, Xun Zhu, Syau-Yun Hsieh, thogonal function (EOF) decomposition and Daniel Smith, Sam Yee, and Larry Paxton the corresponding principal component analysis (PCA) technique to capture the modes of spatial and temporal variability observed in the Applied Physics Laboratory, John Hopkins Uni- ionosphere. The spectral analysis of the differ- versity, MD, USA ent time series of reveals how different mechanisms such as solar flux variation, change of the Energetic particles and solar X-ray and ul- orbital declination, nonlinear mode coupling, traviolet (XUV) irradiance have important in- lower atmosphere forcing, and geomagnetic ac- fluences on the chemistry, energetics, and dy- tivity are separated and expressed in different namics of the ionosphere and thermosphere modes. (IT) via direct energy deposition, effects on chemically active minor constituents, and mod- We also examine similar analysis performed ulation of ion-neutral frictional heating. on output from the Thermosphere- Ionosphere- Electrodynamics General Circulation Model In addition, waves that originate in the tro- (TIE-GCM) to provide insight for the inter- posphere grow in amplitude as they travel up- pretation of the observed phenomena. In this wards into decreasing density at higher alti- talk we examine the relationship between the tudes where they become the most prominent variability observed in mesospheric and lower dynamical features of the ITM. At low lati- thermospheric dynamical fields to variations tudes, the wind-driven E-region dynamo gener- observed in the low latitude ionosphere us- ates large-scale electric fields, causing upward ing these long-term global observations and plasma drifts that combine with pressure forces through simulations using the TIE-GCM. and gravity to form the equatorial ionization anomaly in electron density. As aresult, vari- TYPE: ORAL ability in E-region winds could translate up- DATE: 2012-03-12 – 08:45 wards into the low-latitude ionosphere. The dominant dynamical feature in the E-region is the diurnal tide, and its longitudinal, seasonal, INVITED - LARGE-SCALE IONO- interannual, and daily variability are important SPHERIC PERTURBATIONS CAUSED factors in understanding the behavior of the BY ATMOSPHERIC WAVES ionosphere. Hanli Liu

Measurements of the XUV spectrum have High Altitude Observatory, National Center for recently become available over various phases Atmospheric Research, Boulder, CO, USA of the solar cycle and in unprecedented wavelength and temporal resolution. At This study will examine two possible the same time, numerous spaceborne and mechansims through which the lower atmo- groundbased platforms have observed elec- sphere can aﬀect the ionospheric variability tron density, and neutral and ion compo- at low latitudes: namely tidal variability due sition and temperature. Recent long-term to its interation with quasi-stationary plane- global observations of the low latitude neu- tary waves, and secondary generation of grav- tral atmospheric and ionospheric structure ity waves excited by the body forcing from revealed by TIMED/SABER, TIMED/GUVI, dissipation of primary gravity waves from the COSMIC/FORMOSAT, TOPEX, JASON, and lower atmosphere. The former may be most

35 ISEA13 - 13th International Symposium on Equatorial Aeronomy significant during stratospheric sudden warm- modulation of GW character, and instability dy- ing events when the quasi-stationary planetary namics that may either extend to high altitudes waves become large, as evidenced by recent or be confined to narrow layers. Modeling of observations. Because the amplitudes of the multi-scale interactions has revealed that large- propagating tides and the tidal variability are scale interactions, GW spectral evolution, and usually strongest in the ionospheric E-region, instability intensities may depend critically on we will focus on the modification of E-region orientations of small- and large-scale motions. dynamo. We will also examine the contribution Modeling of the various instability dynamics of various tidal components to the wind dy- has likewise shed light on measurement accura- namo change, as well as the dependence of the cies and highlighted the potential for measure- ionospheric responses to solar activities. The ment biases in radar and in situ measurements. secondary gravity waves, on the other hand, can introduce large wind perturbations in both TYPE: ORAL E and F regions. Depending on the local time, DATE: 2012-03-12 – 09:20 the wind dynamo in the E or/and F regions are affected. The impacts on the ionospheric plasma drifts and plasma transport can extend GRAVITY WAVE GENERATION BY after local-midnight. CONVECTION AND MIDDLE ATMO- SPHERE RESPONSE TYPE: ORAL 1 2 1 DATE: 2012-03-12 – 09:00 Robert Vincent , Joan Alexander , Iain Reid , Sujata Kovalam1, Andrew MacKinnon1, and Bronwyn Dolman3 INVITED - GRAVITY WAVE COUPLING, INTERACTIONS, AND INSTABILITIES 1 University of Adelaide, Australia IN THE MLTI 2 Colorado Research Associates, Boulder, CO, USA Dave Fritts 3 ATRAD, Australia

NorthWest Research Associates, Colorado Re- The TWPICE campaign centred on Darwin search Associates Division, Boulder, CO, USA (12°S, 131°E) in northern Australia in January- February 2006 provided an opportunity to study This talk will review recent advances in gravity wave generation by convection and the modeling of gravity wave (GW) propagation, associated wave propagation and momentum wave-wave and wave-mean flow interactions, transport. The project used a variety of radars and instability dynamics expected to be impor- to study the spatial and temporal variability of tant in the MLTI. Specific topics will include: rainfall and the associated latent heat release 1. momentum transport by maintained and lo- during large thunderstorms. A high-resolution calized GWs and implications for GW structure numerical model utilized the latent heat re- and propagation, 2. GW instability and turbu- lease to compute the spatial and geographic lence generation at large spatial scales in the variation of gravity wave generation and prop- MLTI, 3. multi-scale GW interactions and in- agation into the lower stratosphere. Gravity stabilities 4. implications of GW instabilities wave ray-tracing techniques were then used to and turbulence for measurements estimate the wave flux penetrating to heights near 90 km, where the results were compared Modeling of GW propagation in deep do- with direct measurements made using a me- mains has revealed important consequences of teor radar. An analysis of meteor radar (MR) momentum flux gradients in time and/or alti- detection techniques is used to assess the reli- tude. These include strong induced mean wind ability of wave fluxes derived from MR obser- shears, self-acceleration of GWs yielding strong vations. It is shown that, provided the meteor

36 ISEA13 - 13th International Symposium on Equatorial Aeronomy rates are high enough, wave energies can be TYPE: ORAL reliably measured. This result is used to ‘cal- DATE: 2012-03-12 – 09:55 ibrate’ the indirect fluxes from the model, including momentum fluxes and the associated wave drag. It is shown that wave fluxes have a STUDY ON VERTICAL PROPAGATION high degree of temporal variability, with conse- OF MEDIUM-SCALE GRAVITY WAVES quent variability in momentum flux deposition OBSERVED DURING THE COPEX and wave drag. A number of events are studied CAMPAIGN in detail. Outcomes can be used to help con- Igo Paulino1, Hisao Takahashi1, Sharon strain gravity wave parameterization schemes. Vadas2, Cristiano Max Wrasse3, Jose Sobral1, Amauri F. Medeiros4, Ricardo Arlen Buriti5, TYPE: ORAL and Delano Gobbi1 DATE: 2012-03-12 – 09:40 1 Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP, Brazil 2 NorthWest Research Associates, Colorado GROUND BASED OBSERVATIONS IN Research Associates Division, Boulder, CO, THE MLT, DAMPED GWS; AND NEW USA LIDAR FOR THE E-REGION (110-200 3 Vale Soluções em Energia, Brazil KM). 4 Departmento de Fisica, Universidade Federal de Campina Grande, Campina Grande, PB, Gary Swenson, Fabio Vargas, Chester Gardner, Brazil John Westerhoff, and Tony Mangognia 5 Universidade Federal de Campina Grande - UFCG, Brazil University of Illinois at Urbana-Champaign, Ur- bana, IL USA We have ray-traced 15 medium-scale gravity waves (MSGWs) observed at Boa Vista Observations of the mesopause region dy- (2.8°N; 60.7°S, dip angle 21.7°) during the namics has been accomplished with correlative Conjugate Point Experiment (COPEX). Ray- instrumentation including lidar, meteor radar, tracing database have been composed by wind and airglow imagers. Gravity waves (GWs) from the TIE-CGM and HWM-93 models, and have been observed at low and mid latitude temperature profiles from the TIMED/SABER over the past 15 years at SOR (Albuquerque, measurements, NRLMSISE-00 and TIE-GCM NM), Maui Hawaii, and now at Cerro Pachon, models. Doppler up-shifted MSGWs in the Chile at the Andes Lidar Observatory (ALO). MLT region reached higher altitudes and Our observations of HF GWs have been studied larger amplitude than un-shifted waves in the to understand the dominant effect of damped thermosphere-ionosphere. Most MSGWs prop- GWs and their effect on the mesopause region. agated upwards up to 140 km of altitude and A second topic will involve considerations to seem to be unlikely candidate to trigger equato- move observational capabilities to higher al- rial plasma bubbles (EPBs) at the F layer bot- titudes than is currently done. The 110-200 tom side. However, five of them propagated up km altitude region is virtually void of mea- to the altitude close to the F layer bottom side, surements, but new methods will be described where they could seed EPBs directly. which can be used to probe the density and TYPE: ORAL temperature structure of this region. Simu- DATE: 2012-03-12 – 10:10 lations using large power aperture Rayleigh lidars ( 10,000 Wm2) will be shown to illustrate the future potential for measurements of this IONOSPHERIC DISTURBANCES AF- largely unexplored region, as well as large aper- TER THE 2011 OFF THE PACIFIC ture resonance with metals and He. COAST OF TOHOKU EARTHQUAKE

37 ISEA13 - 13th International Symposium on Equatorial Aeronomy

OBSERVED BY THE GPS RECEIVER is the rare events in number, but is a good ex- ARRAY IN JAPAN ample to study the wave propagation from the lower atmosphere to the thermosphere and the A. Saito1, T. Tsugawa2, Yuichi Otsuka3, Michi ionosphere because the source is specified in Nishioka2, T. Iyemori1, M. Matsumura1, S. time and space. In the presentation, the re- Saito4, Chia-Hung Chen1, Y. Goi1, and N. lationship of the ionospheric disturbances with Choosakul5 tsunami and the geomagnetic field variations will be discussed also. 1 Kyoto University, Kyoto, Japan 2 National Institute of Information and Com- TYPE: ORAL munications Technology, Japan DATE: 2012-03-12 – 10:25 3 Solar-Terrestrial Environment Laboratory, Nagoya University, Japan 4 Electronic Navigation Research Institute, INFLUENCE OF 2-DAY PLANETARY Japan WAVE IN THE EQUATORIAL IONO- 5 Rajamangala University of Technology SPHERE Thanyaburi, Thailand Hisao Takahashi1, Mangalathayil Ali Abdu1, Ionospheric disturbances were observed af- Inez Staciarini Batista1, Lourivaldo Mota ter the M9.0 offthe Pacific coast of Tohoku Lima2, Cristiano Max Wrasse 3, Amelia Ono- Earthquake by the GPS receiver array in Japan hara 1, M. Goreti S. Aquino 1, and Paulo Prado on March 11, 2011. The two-dimensional Batista1 structures of the disturbances generated by earthquakes were detected for the first time in 1 Instituto Nacional de Pesquisas Espaciais - high temporal and spatial resolution. There INPE, Sao Jose dos Campos, SP, Brazil were four types of the disturbances: 1) fast 2 Universidade Estadual da Paraíba - UEPB, propagating structures appeared at first, 2) cir- Brazil cular wave fronts propagating from the epicen- 3 Vale Soluções em Energia, Brazil ter, 3) periodic oscillation in four minutes, and 4) plasma depletion in the vicinity of the epi- In the South American equatorial region center. The first structures were attributed to over Brazil at Fortaleza (3.8?S, 38.6?W), we the Rayleigh wave on the surface. The atmo- observed 2-day oscillation in the day to day spheric gravity waves generated in the lower variability of the ionospheric F layer maximum thermosphere would generate second co-centric critical frequency (foF2) during the period of structures. The center of the circular wave January to February. During the same pe- fronts is southeast of the epicenter that was riod, the MLT winds observed at Cariri(7.4?S, the source region of tsunami. It is interpreted 36.5?W) demonstrated the presence of Plane- that the uplift of the sea surface generated the tary 2-day wave. Therefore we studied possi- tsunami and atmospheric wave, and the atmo- ble coupling structure of the 2-day wave into spheric wave in the acoustic mode propagated the ionosphere. Plasma transport by thermo- upward and reached the thermosphere and the spheric meridional wind arising from modula- ionosphere. The acoustic wave resonance be- tion of tidal field by the 2-day wave might have tween the lower thermosphere and the sea sur- important roles on the 2-day oscillation of foF2 face would cause the periodic oscillation of to- in the ionosphere. Influence of the planetary tal electron content in four minutes. This pe- waves in generation of plasma bubbles are also riod is consistent with the model prediction of discussed. the acoustic resonance. The plasma depletion above the epicenter could be generated by the TYPE: ORAL increase of the recombination rate of plasma. DATE: 2012-03-12 – 11:10 The ionospheric variation after the earthquake

38 ISEA13 - 13th International Symposium on Equatorial Aeronomy

SIMULATED EQUINOCTIAL ASYMME- INVITED - IMPACT OF PLANETARY TRY OF THE IONOSPHERIC VERTICAL WAVES ON THE IONOSPHERE DURING PLASMA DRIFTS JANUARY 2009

1 1 Zhipeng Ren , Weixing Wan , Jiangang Tzu-Wei Fang1, Tim Fuller-Rowell1, Rashid 2 2 Xiong , and Libo Liu Akmaev2, Fei Wu1, and Houjun Wang1 1 Institute of Geology and Geophysics, Chinese 1 CIRES, University of Colorado Boulder, CO, Academy of Sciences, China USA 2 Beijing National Observatory of Space Envi- 2 NOAA Space Weather Prediction Center, ronment, Institute of Geology and Geophysics, Boulder, CO, USA Chinese Academy of Sciences, Beijing, China

Using TIDM-IGGCAS-II model and tidal Studies have demonstrated higher plane- winds below 105 km from TIMED/TIDI ob- tary wave activity during a major stratospheric servations, we study the influence of the lower warming (SSW) event in northern hemisphere thermospheric tidal winds below 105 km on the winter. It is also known that the quasi two-day equinoctial asymmetry of the equatorial verti- planetary wave tends to occur near the end of cal E×B plasma drifts. Although a series of January in the southern hemisphere. Signifi- other non-migrating tides also affect the verti- cant two-day and five-day planetary wave activ- cal drift asymmetry, the simulated equinoctial ities at equatorial regions in January 2009 are asymmetry in vertical drift are mainly driven also observed using the GPS-TEC. This work by the migrating diurnal tide (DW1), migrat- conducts model simulation to study the effects ing semidiurnal tide (SW2), DE3, and DW2 of various planetary waves on the ionosphere- non-migrating tides. The asymmetry in day- thermosphere system. The Whole Atmospheric time vertical drift varies with local time and Model (WAM) is capable of simulating real longitude, and mainly shows three features. sudden stratospheric warming (SSW) events. First, the simulated daytime vertical drift dur- Driving the Global Ionosphere Plasmasphere ing March Equinox is larger than that during model (GIP) with the thermospheric winds September Equinox in most of longitudinal sec- from WAM, the responses of ionospheric pa- tors. This asymmetry is mainly driven by the rameters including NmF2, TEC, and electro- semiannual oscillation (SAO) of the migrating dynamics are estimated and compared with diurnal tide in the tropical MLT region, and the observations. The thermospheric winds show equinoctial asymmetry of the migrating semid- a strong two-day perturbation at low- and iurnal tide also play an important role in the mid-latitudes at mesosphere and lower thermo- generation of this asymmetry. Second, the day- sphere (MLT) region in January 2009 before time vertical drift asymmetry in Eastern Hemi- the peak SSW occurs. The NmF2 at certain sphere is more significant than that in Western locations also demonstrate the corresponding Hemisphere. Our simulation suggests that the two-day fluctuations. The possibility of the en- longitudinal variation of the geomagnetic fields hanced planetary wave activities in modulating and DW2 tides play important roles in the gen- the day-to-day variability of electrodynamics is eration of this hemisphere difference. Thirdly, also examined. In this presentation, we will there is an obvious wavenumber-4 longitudi- focus on the planetary wave signatures in the nal structure in the vertical drift asymmetry. ionospheric parameters and discuss the role of Our simulation suggests that this wavenumber- these planetary waves in day-to-day variability 4 structure is mainly driven by the equinoctial of the ionospheric responses during the January asymmetry of the DE3 tide. 2009.

TYPE: ORAL TYPE: ORAL DATE: 2012-03-12 – 11:25 DATE: 2012-03-12 – 11:40

39 ISEA13 - 13th International Symposium on Equatorial Aeronomy

ATMOSPHERE-IONOSPHERE COU- various parts of the equatorial atmosphere, PLING EFFECTS AT LOW LATITUDE right from stratosphere to the thermosphere- OBSERVED BY FORMOSAT-3/COSMIC ionosphere regions. Analysis based on the measurements using a variety of instruments over 1 1 Charles Lin , Jia-Ting Lin , and Loren C. Trivandrum (8.5o N, 77 o E, 0.5o N diplat.), 2 Chang a geomagnetic dip equatorial station in In- dia, revealed that the equatorial atmosphere- 1 National Cheng Kung University, Taiwan ionosphere as a whole respond significantly to 2 National Central University, Taiwan the abrupt changes in energetics and dynamics Recent studies have shown that the iono- over polar stratosphere. As far as the equatorial spheric plasma structure is modulated by up- stratosphere is concerned, the important obser- ward propagating atmospheric tides of tro- vations are (i) the temperature at 30 km (10 posphere origins and planetary waves gener- hPa) over Trivandrum shows a sudden cooling ated during the stratospheric sudden warming 10 days prior to the SSWs (ii) appearance and (SSW) period. These effects of lower atmo- progression of a zero-wind line in the zonal- spheric origins modify the ionospheric electro- mean zonal wind at 30 km from tropics to dynamic and result in longitudinal, latitudinal, the pole 60 days prior to the SSWs and (iii) and altitudinal variations of the low-latitude an enhanced PW activity of quasi 16-day pe- equatorial ionization anomaly (EIA). In this riodicity and its propagation from equator to study, three-dimensional electron density ob- the Pole. At mesospheric altitudes, an over- servations derived from GPS radio occultation all enhancement in mesopause temperature and sounding of FORMOSAT-3/COSMICduring amplified planetary wave activity is observed 2007-2010 are utilized to study the annual prior to the SSW. When it comes to the lower and monthly variations of the atmospheric thermosphere-ionosphere region, the SSW is tidal signatures in the ionosphere. This study found to be modulating the electrodynamics also investigates SSW effects to the low- in the form of favored occurrences of Equa- latitude ionosphere from the constructed three- torial Counter Electrojets (CEJs) with a quasi dimensional electron density maps. According periodicity of 16-days. It is interesting to note to the stratospheric temperature observation of that intense SSW events were associated with FORMOSAT-3/COSMIC, the SSW occurs ev- stronger CEJs. These aspects are discussed in ery year during 2007-2010 but the occurring terms of the prevailing changes in the dynamics months and durations are different. The iono- and electrodynamics over the equatorial region. sphere response to the SSW effect is expected to vary due to these annual differences. TYPE: ORAL DATE: 2012-03-12 – 12:15 TYPE: ORAL DATE: 2012-03-12 – 12:00 GRAVITATIONAL TIDES AND THEIR INFLUENCE ON THE THERMOSPHERE IMPACTS OF POLAR STRATOSPHERIC Jeffrey Forbes1, Xiaoli Zhang1, and Sean SUDDEN WARMING ON THE EQUATO- 2 RIAL ATMOSPHERE-IONOSPHERE RE- Bruinsma GION 1 University of Colorado Boulder, CO, USA 2 C. Vineeth and T. K. Pant CNES, Toulouse, France

Space Physics Laboratory, Vikram Sarabhai Renewed interest in lunar tidal inﬂuences on Space Centre, Trivandrum, India the ionosphere-thermosphere (IT) system has emerged in connection with Fejer’s discovery This study discusses the impact of po- of a possible connection between stratospheric lar Stratospheric Sudden Warmings (SSW) on warmings and lunar tidal perturbations of the

40 ISEA13 - 13th International Symposium on Equatorial Aeronomy equatorial ionosphere. By virtue of its gravi- mond, and Raymond Roble tational force on the solid earth, oceans and atmosphere, the moon produces perturbations High Altitude Observatory, National Center for in the temperature, density, pressure and wind Atmospheric Research, Boulder, CO, USA fields of earth’s atmosphere. Lunar tidal winds in the dynamo region (ca. 100-150 km) can Observations during the last very low solar furthermore generate electric fields that map minimum showed that the ionosphere and ther- into the F-region and redistribute ionospheric mosphere are not only influenced by geospace plasma. Direct penetration (propagation) of but also by tropospheric weather. One of the lunar tides to F-region heights can also trans- extreme meteorological events is sudden strato- port ionospheric plasma. The most important spheric warming (SSW) when the polar vor- lunar tidal components in terms of forcing are tex of eastward winds in the winter hemisphere M2 (period = 12.42 h), N2 (period = 12.66 is abruply slowed down or even splits. SSW h) and K2 (period = 11.97 h). There is also a is caused by strong planetary wave activity in solar gravitational tide S2 (period = 12.00 h). the troposphere. Due to the strong planetary In this paper, the atmospheric response up to wave activity the dynamics of the mesosphere 400 km to solar and lunar gravitational forcing and thermosphere are changed. There is obser- is explored using the Global-Scale Wave Model vational evidence of signals of SSW events in (GSWM), with particular emphasis on sensitiv- the neutral temperature and winds, equatorial ity of the response to zonal-mean winds de- zonal electric fields, and electron and neutral rived from observational data in the lower and densities. middle atmosphere (i.e., TIMED-SABER thermal gradient winds, MERRA Reanalysis prod- The National Center for Atmospheric ucts). Comparisons are performed between Research (NCAR) Thermosphere-Ionosphere- monthly-mean lunar tidal determinations from Mesosphere-Electrodynamics General Circula- GSWM, and the corresponding lunar tides in tion Model (TIME-GCM) can model the ob- SABER temperatures between 90 and 110 km served features in the stratosphere and meso- and CHAMP densities at 400 km. The GSWM sphere during SSW events. We will examine is also used to explore atmospheric resonance the effects of SSW under realistic geospace behavior at periods between 10 and 14 hours. variability for 2006. We quantify the effects In preliminary results we find the aggregate of strong planetary wave forcing by compar- effects of the M2, N2, K2 and S2 monthly- ing with a control simulation. The tidal propa- mean gravitational tides to be as large as 20- gation is changed due to different background 30 m/sec in dynamo-region winds and 3-6% in winds and the nonlinear interaction between density near 400 km, large enough to impose the planetary wave and tides. We quantify the non-negligible day-to-day variability on the IT changes of major tidal components. We exam- system. The sensitivity of gravitational tides to ine their influence on the zonal electric fields, stratwarm-induced zonal mean wind and tem- and the changes in the ionosphere and upper perature changes is also explored. thermosphere. Finally, we will assess the simulation of the SSW event in the context of ob- TYPE: ORAL servations. DATE: 2012-03-12 – 12:30 TYPE: ORAL EFFECTS OF SUDDEN STRATO- DATE: 2012-03-12 – 12:45 SPHERIC WARMING SIMULATED BY THE THERMOSPHERE-IONOSPHERE- P3.02 SEASONAL VARIABILITY OF MESOSPHERE-ELECTRODYNAMICS- GRAVITY WAVE MOMENTUM FLUX IN GCM THE MLT OVER SAO JOAO DO CARIRI Astrid Maute, Maura E Hagan, Arthur Rich- (7°S; 36°W).

41 ISEA13 - 13th International Symposium on Equatorial Aeronomy

V.F. Andrioli1, Dave Fritts2, Paulo Prado Coupling between mesosphere-thermosphere Batista1, and Barclay Robert Clemesha1 regions is a very activity research field. Grav- ity waves (GWs) propagating upwards trans- 1 Instituto Nacional de Pesquisas Espaciais - port momentum and energy from lower/middle INPE, Sao Jose dos Campos, SP, Brazil atmosphere to upper atmospheric layers. 2 NorthWest Research Associates, Colorado The study of the coupled Mesosphere- Research Associates Division, Boulder, CO, Thermosphere system due to gravity waves USA at low latitudes requires observations of multiple airglow layers via all-sky imaging system. In the present work we have used Hock- The OH, OI557.7 and OI630 nm airglow emis- ing’s (2005) technique to infer the monthly sion and ionospheric observations using a CADI mean gravity wave (GW) momentum fluxes and type ionosonde were carried out at Sao Jose their seasonal variability over Sao Joao do Cariri dos Campos (23.2oS, 45.9oW)-Brazil, near (7°S; 36°W). We also have used numerical sim- the southern crest of equatorial ionospheric ulations to test the ability of Skyimet me- anomaly. In this study were analyzed four dif- teor radars to measure GW momentum fluxes. ferent cases in the airglow emissions as follow: From theses tests we can conclude that, pro- A) with presence of GWs in the OH and ab- vided allowance is made for contamination by sence of GWs in OI 557.7nm, B) absence of tides, we can measure GW momentum fluxes GWs in OH and presence of GWs in OI 557.7 with reasonable accuracy on a monthly basis, nm, C) presence of GWs in both OH and OI at least at altitudes at which meteor counts 557.7 nm, D) absence of GWs in both OH are relatively high, typically from 87 to 94.5 and OI 557.7 nm. The response of the ther- km, with greater accuracies near the peak of mosphere and ionosphere to the presence (or the meteor distribution in altitude. We have absence) of GWs at mesospheric heights is an- analyzed the data from June 2004 to Decem- alyzed during 4 events in each case A-D listed ber 2008 and the results are encouraging. We above. observed mainly annual variability in the u’w’ component, being positive from March to Au- TYPE: POSTER gust. On the other hand, we observe mainly DATE: 2012-03-13 – 17:35 a 4 month oscillation in the v’w’ component, being positive from February to April, July to August, and October to November. P3.04 EVIDENCE OF COUPLING BE- TWEEN MIDDLE ATMOSPHERE AND TYPE: POSTER IONOSPHERE DURING 2009 SUD- DATE: 2012-03-13 – 17:35 DEN STRATOSPHERIC WARMING THROUGH LUNAR SEMIDIURNAL TIDES P3.03 STUDY OF MESOSPHERE- THERMOSPHERE-IONOSPHERE COU- Jiangang Xiong1, Weixing Wan2, Libo Liu1, PLING AT LOW LATITUDE and Baiqi Ning1

Alan Monteiro1, Marcio Muella1, Fabio 1 Beijing National Observatory of Space Envi- Vargas2, José Valentin Bageston3, José Ri- ronment, Institute of Geology and Geophysics, cardo Abalde1, and Paulo Fagundes1 Chinese Academy of Sciences, Beijing, China 2 Institute of Geology and Geophysics, Chinese 1 Universidade do Vale do Paraíba, Sao Jose Academy of Sciences, China dos Campos, Brazil 2 University of Illinois at Urbana-Champaign, The sudden stratospheric warming (SSW) Urbana, IL USA in the winter of 2008/2009 is the strongest rec- 3 Instituto Nacional de Pesquisas Espaciais - orded SSW event. The middle atmosphere and INPE, Sao Jose dos Campos, SP, Brazil ionosphere over Beijing (39o50’N, 116o30’E)

42 ISEA13 - 13th International Symposium on Equatorial Aeronomy were also affected by the SSW. The response Terrestrial Magnetism, Ionosphere and Radio of middle atmosphere and io-nosphere over Bei- Wave Propagation RAS, Kaliningrad, Russia jing to the SSW was not the same as that over 2 High Altitude Observatory, National Center high latitude or low lati-tude sites, based on in for Atmospheric Research, Boulder, CO, USA situ observations of meteor radar and ionosonde 3 Institute of Solar-Terrestrial Physics, Irkutsk, in Beijing, and data of satellite and other equip- Russia ment. On 24 January of 2009, all conditions 4 Haystack Observatory, Massachusetts Insti- of Major SSW were satisfied. We call the tute of Technology, Westford, Massachusetts, day as SSW peak. A few days before the USA SSW peak, zonal winds in the mesosphere and 5 Department of Physics and Astronomy, Uni- stratosphere reversed from eastward to west- versidade do Vale do Paraiba, Sao Jose dos ward. The westward zonal wind persisted for Campos, Brazil several days around the SSW peak. Both tem- 6 Universidade do Vale do Paraíba, Sao Jose peratures in the stratosphere and mesosphere dos Campos, Brazil decreased during the SSW. That means the 7 Radio Observatorio de Jicamarca, Instituto tempera-ture variations over Beijing at meso- Geofísico del Perú, Lima, Perú sphere and stratosphere were affected by cir- culations at high latitude and low latitude re- Interaction between the lower and upper spectively. The critical frequency of F2 layer atmospheric layers is a challenging problem. ( ) and peak height (hmF2) decreased 1 MHz In general, some of the underlying mecha- and 8 km in the afternoon during the SSW. nisms responsible for the coupling between the TEC (Total electron content) increased in the stratosphere, thermosphere and ionosphere are morning and dropped in the afternoon. The lu- currently known. The Sudden Stratospheric nar semidiurnal tides of mesospheric wind also Warming (SSW) is an interesting phenomenon increased rapidly. The semidiurnal var-iation of to investigate the interrelation between differ- TEC and zonal semidiurnal tide at 100km were ent atmospheric regions. SSW events have almost in phase around the SSW peak. This is recently received significant attention, with the first observational evidence that enhanced overwhelming experimental evidence of strong lunar semidiurnal tides in the mesosphere re- effects in the ionosphere and thermosphere. sulted in the variation of the TEC through elec- However, the understanding of physical mech- trodynamic process during daytime. anisms leading to such effects is not sufficient. This report presents an investigation of iono- TYPE: POSTER spheric response to the 2009 SSW event, which DATE: 2012-03-13 – 17:35 was during a period characterized by low solar and geomagnetic activity. We performed model runs using the Thermosphere Ionosphere P3.05 IONOSPHERIC VARIABILITY Mesosphere Electrodynamics General Circula- DURING SSW 2009 EVENT – TIME- tion Model (TIME-GCM) with the boundary GCM AND GSM TIP MODEL RESULTS conditions at 30 km according to data from AND OBSERVATIONS European Centre for Medium-Range Weather Maxim Klimenko1, Hanli Liu2, Vladimir Forecasts (ECMWF) data. Then TIME-GCM Klimenko1, Fedor Bessarab 1, Jurij Nina output at 80 km was used as lower bound- Korenkov1, Raymond Roble2, Konstantin ary conditions for driving Global Self-consistent Ratovsky3, Larisa Goncharenko4, Yogeshwar Model of the Thermosphere, Ionosphere and Sahai5, Jurij Nina Korenkov1, Ivan Karpov1, Protonosphere (GSM TIP). Thus we obtained Artem Vesnin3, Marina Chernigovskaya3, Paulo the stratospheric warming ionospheric effects Fagundes6, Alessandro De Abreu5, Rodolfo De with used the TIME-GCM and GSM TIP mod- Jesus5, and Percy Condor7 els. We compare two models’ results with ground-based ionospheric data at middle and 1 West Department of Pushkov Institute of low latitudes obtained by Incoherent Scat-

43 ISEA13 - 13th International Symposium on Equatorial Aeronomy ter Radar (ISR) in Millstone Hill, ionosondes in the semi diurnal tidal components through in Kaliningrad, and Siberia (Norilsk, Yakutsk, wave-tidal interactions are responsible for such Irkutsk), South America (Jicamarca, Palmas changes in the equatorial electrodynamics. For and Sao Jose dos Campos), and GPS receivers the ‘ﬁrst time’, the study brings out the re- in North and South America. sponse of night time equatorial ionosphere and daytime thermosphere to the SSW induced TYPE: POSTER eﬀects. DATE: 2012-03-13 – 17:35 TYPE: POSTER DATE: 2012-03-13 – 17:35 P3.08 SIGNATURES OF SUDDEN STRATOSPHERIC WARMING ON THE EQUATORIAL IONOSPHERE- P3.09 DIURNAL TIDE AND 2-DAY THERMOSPHERE SYSTEM WAVE COUPLING IN THE METEOR WINDS AT CACHOEIRA PAULISTA S. G. Sumod, T. K. Pant, C. Vineeth, and M. AND SãO JOãO DO CARIRI, BRAZIL, M. Hossain OBSERVED DURING JUNE-JULY 2008

Space Physics Laboratory, Vikram Sarabhai 1 1 Space Centre, Trivandrum, India Lourivaldo Mota Lima , Edvaldo O. Alves , Amauri F. Medeiros 2, Ricardo Arlen Buriti3, 4 The present study comprehensively Paulo Prado Batista , and Barclay Robert 4 brings out the quiet time equatorial iono- Clemesha sphere/thermosphere variability over Trivan- 1 drum (8.5° N, 77°E, 0.5° N diplat.), in India, Universidade Estadual da Paraíba - UEPB, during both night and daytimes, vis-à-vis the Brazil 2 SSW event of January 2008. It has been ob- Departmento de Fisica, Universidade Federal served that the entire EITS exhibits significant de Campina Grande, Campina Grande, PB, variability during the SSW period. EITS pa- Brazil 3 rameters like Equatorial Electrojet (EEJ), F2 Universidade Federal de Campina Grande - layer critical frequency (foF2), F1 layer base UFCG, Brazil 4 height (h’F), Total Electron Content (TEC) Instituto Nacional de Pesquisas Espaciais - and 630 nm thermospheric dayglow showed INPE, Sao Jose dos Campos, SP, Brazil clear cut signatures of the SSW induced effects. Important observations are : (1) En- During the time interval from June to July hanced EEJ in the morning and occurrence of 2008 the neutral winds obtained in the MLT unusually strong CEJ during the afternoon pe- region by meteor radar systems at São João do riods (2) consistent decrease in foF2 at 10:00 Cariri (7.4°S, 36.5°W) and Cachoeira Paulista IST, followed by an afternoon increase and an- (22.7°S, 45.0°W) presented typical variations other decrease after 21:00 IST and (3) Strong consistent with nonlinear coupling between at- Pre-Reversal Enhancement (PRE) at 18:30 mospheric wave modes. The spectral analy- IST followed by a significant decrease in the sis of the hourly winds for both sites shows h’F at 21:00 IST (4) diurnal maximum of distinct power spectrum with peaks associated TEC occurring at an earlier local time, com- with diurnal and semidiurnal tides, quasi-two- pared to non SSW period, and a decrease in day waves and 16-hour oscillations, mainly in the afternoon-evening period and (5) unusual the meridional wind component. The quasi si- decrease in overall 630 nm dayglow and pres- multaneous presence of these waves suggested ence of strong noon time bite outs. It is sug- that the 16-hour waves could have been gener- gested that dynamical perturbations associated ated from nonlinear interactions between the with the SSW and subsequent modifications diurnal tide and 2-day waves. Additionally,

44 ISEA13 - 13th International Symposium on Equatorial Aeronomy these relationships have been investigated us- TYPE: POSTER ing bispectral analysis and the results reinforce DATE: 2012-03-13 – 17:35 our interpretation.

TYPE: POSTER P3.12 IONOSPHERIC MIGRATING DATE: 2012-03-13 – 17:35 TIDE MODIFICATION DURING THE 2008-2009 STRATOSPHERIC SUDDEN WARMING P3.10 MESOSPHERIC AND LOW THER- Jia-Ting Lin1, Charles Lin1, and Loren C. MOSPHERIC DYNAMICS OVER 7.4 S Chang2 AND 22.7 S 1 National Cheng Kung University, Taiwan 1 Luciana Rodrigues De Araújo , Lourivaldo 2 National Central University, Taiwan Mota Lima1, Paulo Prado Batista2, and Bar- clay Robert Clemesha2 In this paper, modifications of the ionospheric tidal signatures during the 2008-2009 1 Universidade Estadual da Paraíba - UEPB, stratospheric sudden warming (SSW) event are Brazil studied by applying atmospheric tidal analysis 2 Instituto Nacional de Pesquisas Espaciais - to ionospheric electron densities observed using INPE, Sao Jose dos Campos, SP, Brazil radio occultation soundings of FORMOSAT- 3/COSMIC. The tidal analysis indicates that Neutral winds estimated from meteor radar the zonal mean and major migrating tidal data have been used to investigate the dy- components (DW1, SW2 and TW3) decrease namics of the MLT region over São João do around the time of the SSW, with 1.5-4 hour Cariri (7.4ºS, 36.5ºW) and Cachoeira Paulista time shifts in the daily time of maximum. The (22.7ºS, 45.0ºW). For both places, the spec- typical ionospheric SSW signature: a semi- tral analysis of the hourly-average winds shows diurnal variation of the ionospheric electron distinct power spectrum with peaks in the tidal density, featuring an earlier commencement periods as well as in the low-frequency oscil- and subsidence of EIA, can be reproduced by lations. Mean zonal winds over São João do differencing the migrating tides before and dur- Cariri show a structure characterized by a semi- ing the SSW period. Our results also indicate annual oscillation, with a flow westward most that the migrating tides represent 80% of the of the time. The mean zonal wind at Ca- ionospheric tidal components at specific lon- choeira Paulista is eastward in most time and gitudes, suggesting that modifications of the presents a semi-annual variation in the 80-90 migrating tides may be the major driver for km altitude range and an annual variation in producing ionospheric changes observed during altitudes above. The amplitudes of the mean SSW events, accounting for greater variability meridional winds were weaker than zonal and than the nonmigrating tides that have been the present an annual variation for both localions. focus of previous studies. The meridional diurnal tide amplitudes showed semi-annual variation with maximum during TYPE: POSTER February-April and August-September. The DATE: 2012-03-13 – 17:35 spectral energy associated with low-frequency oscillations ranging from 2 to 20 days can be P3.13 COMPARATIVE STUDY OF seen in the zonal wind component along the IONOSPHERIC RESPONSE TO RE- time. The meridional wind component ex- CENT STRATOSPHERIC SUDDEN hibit intense spectral energy associated with WARMINGS quasi-two-day wave during January-February and during other times of the year, but with Larisa Goncharenko1, Anthea Coster2, and less intensity. Jorge Chau3

45 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 Haystack Observatory, Massachusetts Insti- MATOLOGY DERIVED FROM TIMED tute of Technology, Westford, Massachusetts, OBSERVATIONS USA 2 MIT Haystack Observatory, Massachusetts Jeng-Hwa Yee1, Elsayed Talaat1, Xun Zhu1, Institute of Technology, MA, USA Jim Russell2, Martin Mlynczak3, Wilbert 3 Radio Observatorio de Jicamarca, Instituto Skinner4, and Larry Paxton1 Geofísico del Perú, Lima, Perú 1 Applied Physics Laboratory, John Hopkins We use GPS TEC, Jicamarca ISR, and University, MD, USA ECMWF ERA interim data to study effects of 2 Hampton University, VA, USA different stratospheric sudden warming (SSW) 3 NASA Langley Research Center, USA events on low-latitude ionosphere in winters of 4 University of Michigan, Ann Arbor, MI, USA 2009, 2010, and 2011. Well documented Jan- uary 2009 major SSW event was the strongest The Stratosphere, Mesosphere and Lower SSW on record, and was associated with en- Thermosphere (SMLT) is a region of the Earth hanced activity of planetary wave 2. The Jan- atmosphere that is very sensitive to external uary 2010 SSW event was marked by a mod- influences from the sun above and lower atmo- erate and prolonged increase in high-latitude sphere below it. Its chemical, momentum and stratospheric temperature, and was associated thermal balance, thus basic states (i.e. pres- with enhanced planetary wave 1. The Febru- sure, density, and temperature, and winds) can ary 2011 SSW event was a minor short-lived change in different time scales due to naturally- warming driven by enhancements in both plan- occurring and/or human-induced changes to etary waves 1 and 2. We examine ionospheric the composition and energy contained within response to these events at three distinct longi- this region. The NASA Thermosphere- tudes: 75W, 25E, and 120E. We report signif- Ionosphere-Mesosphere Energetics and Dynam- icant ionospheric disturbances during all SSW ics (TIMED) mission, since its successful events, including a minor event in 2011. The launch in December 2001, has provided for the strength and temporal development of iono- first time a comprehensive view of the basic spheric response varies with longitude, with structure and its variabilities of the SMLT sys- largest variations due to SSW observed at 75W tem during the descreasing phase of past solar and 120E. Analysis of stratospheric parame- cycle, extended solar minimum and current as- ters indicates that SSW events lead to the cending phase of this solar cycle. This paper increase in ozone concentration in the low- gives a 10-year climatological view of the SMLT latitude stratosphere as well as to the increase system as observed by the TIMED spacecraft in longitudinal variation of ozone. Variations and reports the characteristics and magnitudes in ozone density could potentially contribute of its temporal and spatial variabilities includ- to the variability of the semidiurnal tide ex- ing tides (migrating and non-migrating tides) cited by ozone heating. Longitudinal asymme- and planetary waves. Examples of the ob- try in ozone density can lead to the excitation served climatology and variabilities will be used of non-migrating tides. Combined effects of to examine and assess our basic understanding these stratospheric variations can significantly of coupled radiative/chemical/dynamical pro- contribute to the variability of the equatorial cesses that occur in the system. ionosphere TYPE: POSTER TYPE: POSTER DATE: 2012-03-13 – 17:35 DATE: 2012-03-13 – 17:35

P3.15 QUIET-TIME VARIABILITY OF P3.14 AN EMPIRICAL MODEL OF MID- THE GPS TEC AND EEJ STRENGTH DLE AND UPPER ATMOSPHERE CLI- OVER INDIAN REGION AND THEIR

46 ISEA13 - 13th International Symposium on Equatorial Aeronomy

CONNECTION TO THE MAJOR SUD- DATE: 2012-03-13 – 17:35 DEN STRATOSPHERIC WARMING (SSW) EVENTS DURING 2005/2006 P3.16 OBSERVED GRAVITY WAVE- Samireddipalle Sripathi and Archana Bhat- GRAVITY WAVE INTERACTION AT tacharyya MESOSPHERIC HEIGHTS Paulo Fagundes1, José Valentin Bageston2, Indian Institute of Geomagnetism, Navi Mum- José Ricardo Abalde1, and Paulo Prado bai, India Batista2

In this paper, quiet-time variabilities of the 1 Universidade do Vale do Paraíba, Sao Jose GPS-TEC collected at several locations in In- dos Campos, Brazil dia along with simultaneous observations of 2 Instituto Nacional de Pesquisas Espaciais - EEJ strength obtained from geomagnetic field INPE, Sao Jose dos Campos, SP, Brazil variations during Jan-Mar 2006 are presented when Sudden Stratospheric Warming (SSW) This study presents and discuss two simul- events occurred. Analysis of the observations taneous mesospheric fronts observed through presented here suggests that strong correlation the OH nightglow emission, using an all-sky exists among the variabilities in EEJ strength imaging system at Palmas (10.2° S, 48.2° W), and GPS-TEC observations. Further inves- Brazil. On May 29-30, 2008, an uncommon tigations using spectral analysis suggest that event of gravity-wave was observed and iden- there exists a large-scale wave like structures tified as an interaction between two meso- with periodicity of quasi 16-day wave in the spheric gravity-wave type fronts. After the TEC observations near EIA quite similar to that two waves cross each other in almost opposite of EEJ strength. Our observations also indi- direction, a great depletion in the OH emis- cate the existence of morning enhancement and sion rate was observed between these fronts. evening reduction of TEC and EEJ strength The two wave fronts extended throughout the and vice versa during SSW events quite sim- north-south extension and propagated in south- ilar to that reported elsewhere. Using these west and northeast direction, respectively. In observations, it is suggested that the quiet- fact, the gravity-waves moved in almost the op- time variabilities seen in the present observa- posite directions, and when they crossed each tions could be caused due to the interaction of other during their passage, a region between upward propagating planetary wave (PW) with the wave fronts showed a band of airglow de- atmospheric tides and produce variabilities in pletion. The airglow depletion between the two both EEJ strength and vertical EXB drift over fronts became wider as the waves moved away equator which in turn affecting the TEC over from each other. The two mesospheric fronts EIA. Wind measurements in the mesospheric showed distinct horizontal wavelengths and pe- altitude over Trivandrum, an equatorial station riods, but very similar observed phase speed. at the same time reveal existence of quasi 16- In addition, meridional and zonal wind com- day wave period in the zonal winds. Since ponents were obtained by a meteor radar op- similar periods have been noticed in the meso- erated in Sao Joao do Cariri (7.4°S, 36.5°W), spheric winds, EEJ strength and TEC obser- Brazil, and temperature observations from the vations over EIA region, it is conjectured that TIMED/SABER satellite were used together the large-scale wave like structures seen in TEC with the wind measurements to characterize might be associated with PWs that is modifying the vertical propagation characteristics of the both EEJ strength and primary eastward elec- observed waves. The large airglow depletion tric field through non linear interactions with seen between the two fronts after the wave- atmospheric tides. wave interaction is a puzzle, but could be explained by photochemistry models forced by dy- TYPE: POSTER namics. Essentially, the observed OH emission

47 ISEA13 - 13th International Symposium on Equatorial Aeronomy depletion will depend on the photochemistry TYPE: POSTER that forms the excited OH and on the local DATE: 2012-03-13 – 17:35 temperature.

TYPE: POSTER P3.19 GRAVITY WAVE SIGNATURES IN DATE: 2012-03-13 – 17:35 MULTIPLE INSTRUMENT DATASETS OBSERVED AT THE ANDES LIDAR OB- SERVATORY

P3.18 ATMOSPHERIC LUNAR TIDE Fabio Vargas and Gary Swenson OBSERVED BY METEOR RADAR AT MIDDLE AND LOW LATITUDES IN University of Illinois at Urbana-Champaign, Ur- BRAZIL bana, IL USA

Ana Roberta Paulino1, Paulo Prado Batista1, The Andes Lidar Observatory (ALO) has Barclay Robert Clemesha1, Ricardo Arlen been built at an altitude of 3000 m on the Buriti2, and Nelson J. Schuch1 top of Cerro Pachon Montain, Chile (30.3S, 70.7W). The station is now fully operational 1 Instituto Nacional de Pesquisas Espaciais - due to the efforts of the Remote Sensing INPE, Sao Jose dos Campos, SP, Brazil and Space Science Laboratory (RSSS) at the 2 Universidade Federal de Campina Grande - University of Illinois at Urbana-Champaign UFCG, Brazil (UIUC). Na Lidar and meteor radar systems were deployed with four airglow sensors that are running in a regular basis (All Sky Imager, Using meteor radar data from three Brazil- Mesosphere Temperature Mapper, Aerospace ian stations [São João do Cariri (7.4° S; 36.5° Infrared Camera and Multichannel Photome- W), Cachoeira Paulista (22.7° S; 45.0° W) and ter). This work will present data from the Santa Maria (29.7° S; 53.8° W)], the atmo- campaign to be held on January 2012 and will spheric semidiurnal lunar tide in the mesosphere show complete characterization of waves (low and lower thermosphere has been studied from and high frequency) perturbing multiple airglow January 2005 to December 2008. Monthly tidal layers, quantify their momentum flux, flux di- amplitudes and phases were determined using vergence and downward heat flux. Because the hourly mean winds in seven layers of four kilo- wind and thermal structure of the mesosphere meter thickness each, centered in 81, 84, 87, can limit the vertical propagation of gravity 90, 93, 96 and 99 km of height. Most of the waves into ionospheric heights, special atten- amplitudes and phases profiles of the lunar tide tion will be given to the onset of to dynamic showed characteristics of vertically propagating and convective instabilities in the region of the waves in the atmosphere. Over São João do mesosphere and lower thermosphere (75-105 Cariri, during almost all year, the amplitudes of km). the meridional component were greater than the zonal one, and the phases presented equa- TYPE: POSTER torial characteristics of Southern Hemisphere. DATE: 2012-03-13 – 17:35 Over Cachoeira Paulista, the mean amplitudes were greater in meridional component and the phases also presented characteristics of South- P3.20 F3 LAYER VARIABILITY DURING ern Hemisphere. Santa Maria presented merid- SSW EVENTS ional amplitudes greater than zonal between November and April. In several aspects, the Maxim Klimenko1, Vladimir Klimenko1, three sites have similarities with the Vial and Artem Vesnin2, Percy Condor3, Konstantin Forbes (1994) atmospheric semidiurnal lunar Ratovsky2, Hanli Liu4, and Alexander tidal model. Karpachev5

48 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 West Department of Pushkov Institute of Christiano GM Brum 1, Vicki Hsu 2, Larisa Terrestrial Magnetism, Ionosphere and Radio Goncharenko3, Johathan Fentzke4, and Sixto Wave Propagation RAS, Kaliningrad, Russia Gonzalez1 2 Institute of Solar-Terrestrial Physics, Irkutsk, 1 Russia Arecibo Observatory, Puerto Rico 2 3 Radio Observatorio de Jicamarca, Instituto University of Illinois at Urbana-Champaign, Geofísico del Perú, Lima, Perú Urbana, IL USA 3 4 High Altitude Observatory, National Center Haystack Observatory, Massachusetts Insti- for Atmospheric Research, Boulder, CO, USA tute of Technology, Westford, Massachusetts, 5 Pushkov Institute of Terrestrial Magnetism, USA 4 Ionosphere and Radio Wave Propagation RAS, Applied Physics Laboratory, John Hopkins Troitsk, Moscow Region, Russia University, MD, USA Although the primary drivers of ionospheric The ionospheric effects of the sudden variability, such as solar ionizing flux and ge- stratospheric warming (SSW) event have be- omagnetic activity, are relatively well under- ing hotly investigated recently. During an stood, the effects of the lower atmosphere SSW, the global thermospheric wind system onto the ionosphere remain elusive. This study is changed, producing abnormal dynamo elec- focuses on the Sudden Stratospheric Warm- tric fields. This results in a change of vertical ing (SSW) events that occurred in January plasma drift at geomagnetic equator. As it is 2010, and presents the spectral analysis results known, the vertical plasma drift at geomagnetic performed on the ion temperatures measured equator is the main driving force for the forma- by the Millstone Hill incoherent scatter radar tion and maintenance of the additional layer (42.6°N, 288.5°E). The period in study occurs (F3 layer) in the near-equatorial ionosphere. So in the last solar minimum which minimizes any it is evident the occurrence of relationship be- influences of the solar activity variation in our tween the F3 layer and SSW effects. The aim of analysis. Preliminary results show the domi- our study is to clarify this relationship. For this nance of the 15-to18 hours, 12 hour and 6-to- reason, we used the observational data of Inco- 7 hours periodicities in the oscillations starting herent Scatter Radars (ISRs) in Jicamarca dur- on Jan. 21, 2010, and lasting for approximately ing different SSW events. Also we performed 2 days. The domain of these three oscillations model runs using the Global Self-consistent vary with altitude. Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) with the boundary TYPE: POSTER conditions at height of 80 km according to the DATE: 2012-03-13 – 17:35 Thermosphere Ionosphere Mesosphere Electro- dynamics General Circulation Model (TIME- GCM) output. GSM TIP model reproduce the P3.23 SUDDEN PHASE ANOMALIES post-sunset F3 layer before and during 2009 DETECTED AT PUNTA LOBOS 2007- SSW event. So we have possibility to consider 2009, PERU in detail the variations of the additional layers Cristian Ferradas1, Edith Macotela1, Walter in an equatorial ionosphere during SSW events. Guevara1, and Jean-Pierre Raulin2

TYPE: POSTER 1 Comisión Nacional de Investigación y Desar- DATE: 2012-03-13 – 17:35 rollo Aeroespacial, Lima, Perú 2 Centro de Radio Astronomía e As- trofísica Mackenzie, Universidade Presbiteriana P3.22 SPECTRAL ANALYSIS OF Mackenzie, Brazil THE MIDLATITUDE ION TEMPERA- TURE RESPONSES TO THE SUDDEN We present results of Sudden Phase STRATOSPHERIC WARMING EVENT. Anomalies (SPAs) detected at Punta Lobos

49 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Station (PLO), Peru. Our work focuses in the Using wind measurements obtained by a study of ionospheric-D layer disturbances due meteor radar located in the equatorial region at to solar X ray flux through VLF waves propa- São João do Cariri (7.4ºS, 36.5ºW) and sim- gation. We calculate the VLF phase advance ulations by the Kyushu University General Cir- due to these disturbances for signals coming culation Model (Kyushu GCM), we studied the from NAA, NWC, NAU, NDK, NPM, and NLK activity and characteristics of equatorial plane- stations. Additionally, we obtain and compare tary scale waves with periods ranging between the values of the minimum X ray flux input ca- 3 and 8 days in the MLT region. In this analy- pable of producing a detectable SPA at PLO sis a data set of the zonal and meridional wind for each path. components, obtained between July 2004 and December 2006, and model simulations corre- TYPE: POSTER sponding to this time interval are used. Pre- DATE: 2012-03-13 – 17:35 liminary analysis shows that the wave activity is significant in the period range of 3-4 days and P3.24 AN INVESTIGATION OF THE AC- 5-7 days in both meteor winds and model sim- TIVITY OF THE EQUATORIAL PLAN- ulations. Wave activity predicted by the model ETARY SCALE WAVES BY USING in the MLT shows a reasonable agreement with WIND OBSERVATIONAL MEASURE- observational results. In this presentation we MENTS AND MODEL SIMULATIONS will show the main features of the wave activity in these two frequency bands and discuss Fabio Egito 1, Yasunobu Miyoshi2, Ricardo the interpretation of these findings in terms of Arlen Buriti3, Hisao Takahashi1, Paulo Prado the theoretical predictions. Batista1, and Barclay Robert Clemesha1 TYPE: POSTER 1 Instituto Nacional de Pesquisas Espaciais - DATE: 2012-03-13 – 17:35 INPE, Sao Jose dos Campos, SP, Brazil 2 Kyushu University, Japan 3 Universidade Federal de Campina Grande - UFCG, Brazil

50 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 4

PLASMA NEUTRAL COUPLING

A systems approach to research requires the identification of the key components of the system and of the pathway through which those components couple. In the upper atmosphere, treating the neutral and ionized fluids as components of the system is attractive, since paradigms are well established for understanding each one separately. However, distinctly new, emergent phenomena occur when the two components act together, and understanding these requires close examination of the coupling and the ways it contributes to feedback and complexity. The coupling can be local in space, as in the case of sporadic ionization layers driven by sheared neutral flows or of neutral atmospheric heating and forcing by neutral and plasma instabilities driven by local sources of free energy. Important also are processes initiated nonlocally, by waves propagating upward from the lower atmosphere or by coupled E and F region and plasmaspheric electrodynamics, for example. Important coupling takes place not only across spatial boundaries (altitudinal, latitudinal) but also across spatial and temporal scales.

This session seeks contributions that will help elucidate the most important communication pathways between the neutral and ionized components of the system and the phenomena they create.

Conveners: P. Roddy, R. Heelis, and E. Nossa

51 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - EFFECTS OF THERMO- indirectly aﬀect the transport of photoelectrons SPHERIC VARIABILITY ON TOPSIDE by rearranging the plasma density. The plasma EQUATORIAL PLASMA TEMPERA- and neutral density proﬁles both play equally TURES important roles in controlling photoelectron escape into the topside. The examples we present Roger H. Varney1, David Hysell1, and Joseph demonstrate important physical links between Huba2 quantities an ISR can measure and other vari- ables which the ISR cannot measure directly. 1 Cornell University, Ithaca, NY, USA 2 Plasma Physics Division, Naval Research Lab- TYPE: ORAL oratory, USA DATE: 2012-03-13 – 10:30

Using the incoherent scatter radar (ISR) technique and full profile analysis the Jica- INVITED - THE IMPACT OF THE marca Radio Observatory is capable of measur- JANUARY 15, 2010, ANNULAR SO- ing electron and ion temperatures up to 1500 LAR ECLIPSE ON THE IONOSPHERIC km. These measurements display a surprising PROPERTIES AT AND NEAR THE amount of day-to-day variability, even during MAGNETIC EQUATOR. extremely quiet conditions. The daytime electron temperatures above 1000 km can differ by 1 500 K or more from one day to the next. We Jean-Pierre St-Maurice , Raj Kumar 2 2 argue that this variability is readily explained Choudhary , and K. M. Ambili by variability in the neutral thermosphere. Us- 1 ing the recently developed SAMI2-PE model University of Saskatchewan, Canada 2 we demonstrate how relatively modest changes Space Physics Laboratory, Trivandrum, India to the empirically specified background neutral temperatures, neutral densities, neutral winds, The path of maximum obscuration for the and electric fields can all substantially change annular solar eclipse of January 15, 2010, the plasma temperatures. For example, a re- crossed the magnetic equator at Trivandrum, duction of the exospheric temperatures by 100 India, in the early afternoon hours. A strong K will lower the electron temperatures in the counter-electrojet was observed shortly after equatorial F-region by 100 K while simulta- maximum obscuration. An unexpected obser- neously raising the electron temperatures in vation was that, as the eclipse passed over- the equatorial topside by over 100 K. SAMI2- head, the F region density peak underwent a PE is an extended version of the SAMI2 iono- large amplitude vertical oscillation, indicating spheric model which includes a detailed treat- that the zonal electric field had been oscillating ment of photoelectron transport. Even though in response to the passage of the eclipse. In- the topside plasma is far above the exobase, deed the inferred oscillation in the zonal electric it is still intimately connected to the thermo- field could also be seen in the magnetometer sphere below through photoelectron transport data, indicating that the electric field turned processes. The primary heat sources for the westward after the time of maximum obscu- topside plasma are photoelectrons which are rity, reaching its largest westward value one produced at lower altitudes and escape into the hour before the end of the local eclipse. These topside. Changes to the thermospheric density data are consistent with a fast eastward mov- profiles will both change the altitudes where ing local neutral wind dynamo generated by photoelectrons are produced by the absorption a low pressure system that would have been of solar EUV and change the ability of photo- triggered by the cold temperatures centered on electrons to escape into the topside. The neu- the region of maximum obscuration with elec- tral winds and electric fields have no effect on trodynamical processes reminiscent of a dou- the production rates of photoelectrons, but still ble "Pre-Reversal-Enhancement" in the electric

52 ISEA13 - 13th International Symposium on Equatorial Aeronomy

ﬁeld. The unusual solar eclipse-induced elec- MLAT=25.4N) and Darwin. The FPIs mea- trodynamics was also accompanied by a reduc- sure thermospheric winds through Doppler shift tion in the Total Electron Content depletion of the 630-nm airglow emission. From these not just at the magnetic equator (in response observations we found a case of MSTIDs on to increased recombination as the plasma was July 23, 2011, when the thermospheric neutral pushed downward) but also, more markedly, in wind was equatorward in the northern hemi- the Equatorial Ionization Anomaly (EIA) zone, sphere (favorable to the Perkins instability) and a further 10 degrees to the north. This latter poleward in the southern hemisphere (unfavor- point clearly shows that the eclipse led to a cut- able to the Perkins instability), suggesting that oﬀin the supply of plasma provided through the the northern hemisphere was a driver of the equatorial fountain, by altering a fundamental MSTIDs for this case. aspect of the equatorial electrodynamics. TYPE: ORAL TYPE: ORAL DATE: 2012-03-13 – 11:10 DATE: 2012-03-13 – 10:50

MEASUREMENT OF THE CHARAC- GEOMAGNETIC CONJUGATE OBSER- TERISTICS OF TIDS USING SMALL VATIONS OF NIGHTTIME MEDIUM- AND REGIONAL NETWORKS OF GPS SCALE TRAVELLING IONOSPHERIC RECEIVERS DISTURBANCES AND THERMO- SPHERIC NEUTRAL WINDS AT MID- Cesar Valladares1, Roibert Sheehan1, and DLE LATITUDES Matthew Hei2

Kazuo Shiokawa1, Yuichi Otsuka1, and Phil 1 Boston College, MA, USA Wilkinson 2 2 Naval Research Laboratory, USA

1 Solar-Terrestrial Environment Laboratory, This report presents the results of dedicated Nagoya University, Japan experiments that were conducted within the 2 IPS Radio and Space Services, Australia framework of the LISN observatory to measure the characteristics of medium-scale (hundreds The nighttime medium-scale traveling iono- of km) TIDs as they transit through the low- spheric disturbances (MSTIDs) over Japan latitude ionosphere. Small arrays of 3 GPS re- tend to have a NW-SE phase surface and prop- ceivers separated from 5 to 20 kms and placed agate southwestward, particularly in summer at the vertices of a triangle were installed at and winter solstice. This phase-surface direc- different locations in Peru to be used as radio- tion suggests that they are caused by iono- interferometers. The first campaign was con- spheric Perkins instability which occurs when ducted in Huancayo between July 17 and July the thermospheric neutral wind is equatorward. 30. TIDs were observed daily, but they appear The nighttime MSTIDs have geomagnetic con- at different times of the day and their effect on jugacy between Japan and Australia, sug- the TEC traces varies markedly. The second gesting electromagnetic coupling between the campaign was carried out near Lima on March northern and southern hemispheres. In this pre- 2009. The high coherence of the TEC pertur- sentation, we show preliminary results of simul- bations within the few km separation allows us taneous measurements of nighttime MSTIDs to estimate the TID travel velocity, its propaga- using all-sky airglow imagers at geomagnetic tion direction, and the scale-size of the distur- conjugate points at Sata (31.0N, 130.7E, geo- bance. These parameters were calculated using magnetic latitude=21.2N) and Darwin (12.4S, two algorithms: the Statistical Angle of Arrival 131.0E, MLAT=22.1S) and Fabry-Perot inter- and Doppler Method for GPS interferometry ferometers (FPIs) at Shigaraki (34.8N, 136.1E, (SADM-GPS) [Afraimovich et al., 1998, 2003]

53 ISEA13 - 13th International Symposium on Equatorial Aeronomy and the cross-correlation method (CCM). Both 10 University of Liege, Belgium methods indicate that on July 20, 2008 be- 11 Cornell University, Ithaca, NY, USA tween 22 and 24 UT several TIDs moved across the small array of GPS receivers with a veloc- Earth’s ionosphere, the ’inner edge of ity near 130 m/s, were directed northward and space’, is a highly variable boundary - influ- had wavelengths close to 450 km. The CCM enced from below by variations in our weather method was also applied to TEC values col- and from above by solar and geomagnetic ac- lected by other LISN GPS receivers that were tivity. It is an accessible natural laboratory to operating hundreds of km away from Huan- study plasma-neutral coupling in weakly ion- cayo. Regardless the large distances, the coher- ized plasmas relevant to processes occurring ence of the TEC traces was high and a phase in all planetary atmospheres. ICON will ad- velocity equal to 150 m/s was obtained using dress the most compelling science issues that data from Piura, Cuzco and Huancayo. Other deal with the coupling of the ionosphere to the GPS receivers placed in the countries of Bolivia, atmosphere below and space above: 1) The Brazil, Chile, Colombia, Ecuador and Peru also highly variable nature of the electric field in detected TIDs on July 20, 2008. Based on this the ionosphere and its potential link to thermo- positive result, we conclude that small and/or spheric wind, 2) the effect of forcing from be- regional arrays of GPS receivers can be used low: how large-scale atmospheric waves couple at low latitudes to study the role that gravity to the ionosphere, and 3) the effect of forcing waves may have on seeding plasma bubbles. from above: how ion-neutral coupling changes during solar and geomagnetically active peri- TYPE: ORAL ods. To address these, ICON will measure all DATE: 2012-03-13 – 11:25 key parameters of the atmosphere and ionosphere simultaneously and continuously by an elegant compilation of remote sensing and in- INVITED - ICON : THE IONOSPHERIC situ measurements. If selected for development CONNECTION EXPLORER by NASA, ICON will launch in late 2016 into a low-inclination orbit that is particularly well Thomas Immel1, Stephen Mende1, Chris suited to address the above scientific problems Englert2, Roderick Heelis3, Harald Frey1, Jerry as they pertain to equatorial aeronomy, and Edelstein1, GeoffCrowley4, Scott England1, to make numerous coordinated measurements Jeffrey Forbes5, John Harlander6, Joseph with ground-based facilities in the region of in- Huba7, Farzad Kamalabadi8, Astrid Maute9, terest. The observational capabilities of ICON Jonathan J. Makela8, Gary Swenson8, An- will be presented as well as an overview of op- drew Stephan2, Jean-Claude Gerard10, Benoit erations plans. Hubert10, David Hysell11, and Pierre Rochus10 TYPE: ORAL 1 University of California Berkeley, CA, USA DATE: 2012-03-13 – 11:40 2 Naval Research Laboratory, USA 3 University of Texas at Dallas, TX, USA 4 Atmospheric and Space Technology Research IONOSPHERE-THERMOSPHERE COU- Associates, Boulder, CO, USA PLING DURING DEEP SOLAR MINI- 5 University of Colorado Boulder, CO, USA MUM 6 St. Cloud State University, Minnesota, USA 7 Plasma Physics Division, Naval Research Lab- S. H. Delay1, P. A. Roddy2, E. K. Sutton2, oratory, USA Russell Stoneback3, Robert Pfaff4, and Cheryl 8 University of Illinois at Urbana-Champaign, Y. Huang2 Urbana, IL USA 9 High Altitude Observatory, National Center 1 Boston College, MA, USA for Atmospheric Research, Boulder, CO, USA 2 Air Force Research Laboratory, USA

54 ISEA13 - 13th International Symposium on Equatorial Aeronomy

3 University of Texas at Dallas, TX, USA neutral winds alone and neglecting other elec- 4 NASA Goddard Space Flight Center, Green- tromagnetic interactions. belt, MD, USA First a neutral wind model is created to Detrended average plasma densities from recreate radar and rocket observations at lo- the Planar Langmuir Probe, zonal drifts from cations where the irregularities have been de- the Vector Electric Field Instrument, and tected. An analytical solution of the problem meridional drifts from the Ion Velocity Meter of stratified shear flow is found using hyper- on C/NOFS show wavenumber-4 periodicity in geometric functions for three-dimensional con- the equatorial region. These wave-like struc- ditions of the neutral wind. Theoretical ex- tures are most prominent during deep solar pressions for the parameters that predict the minimum. Their climatology appears to be ap- morphology of the irregularities are found. A proximately similar to that of DE3 nonmigrat- validation of the theoretical model is done by ing tides. In addition, broad plasma decreases comparing the results with radar observations. (BPDs), deep reductions in plasma density (up to 90%) occurring over large longitudinal ex- A sensibility analysis of the model allows tents (up to 4.5 hours of local time), appear as us to find an interdependence between wind minima in the tidal pattern. Reductions in neu- parameters and the Brunt-Väaisälä frequency, tral density were observed in the same locations creating a novel methodology to determining during the same periods of time. Dawn deple- the neutral scale height based in the character- tions [Gentile et al., JGR (2011)] observed at istics of the observed irregularities. DMSP altitudes have been compared with the TYPE: ORAL C/NOFS observations. These large plasma de- DATE: 2012-03-13 – 12:15 pletions which coincide in longitude with the BPD observations, occur in regions of downward meridional drift. We suggest that these P4.02 COMPARISON OF OBSERVA- features are related to tidal forcing propagating TIONS OF SPORADIC-E LAYERS IN upwards from low altitudes. THE NIGHTTIME AND DAYTIME MID- LATITUDE IONOSPHERE TYPE: ORAL DATE: 2012-03-13 – 12:00 Robert Pfaff1, Henry Freudenreich1, Doug Rowland1, JeffKlenzing1, James Clemmons2, Miguel Larsen3, Erhan Kudeki4, Steven THEORETICAL MODEL FOR ES IR- Franke4, Julio Urbina5, and Terry Bullet6 REGULARITIES CAUSED BY NEUTRAL WINDS 1 NASA Goddard Space Flight Center, Green- belt, MD, USA Eliana Nossa and David Hysell 2 The Aerospace Corporation, USA 3 Clemson University, Clemson, SC, USA Cornell University, Ithaca, NY, USA 4 University of Illinois at Urbana-Champaign, Urbana, IL USA Ionospheric echoes have been detected by 5 Communications and Space Sciences Labora- coherent radars at midlatitudes during summer tory, Pennsylvania State University, University nights when the Es is strong but patchy. One Park, PA, USA of the possible causes of this irregularity is the 6 University of Colorado Boulder, CO, USA interaction between charged and neutral particles. Big neutral wind shears have been ob- A comparison of numerous rocket exper- served at these latitudes and heights. This pa- iments to investigate mid-latitude sporadic-E per presents a theoretical analysis, characteriz- layers is presented. Electric field and plasma ing the phenomena as if it was originated by density data gathered on sounding rockets

55 ISEA13 - 13th International Symposium on Equatorial Aeronomy launched in the presence of sporadic-E layers this study, geomagnetic conjugate observations and QP radar echoes reveal a complex electro- of the plasma bubbles at low latitudes with dynamics including both DC parameters and thermospheric neutral winds and airglow im- plasma waves detected over a large range of ages were reported for the first time. The scales. We show both DC and wave electric plasma bubbles were observed at Kototabang fields and discuss their relationship to intense (0.2S, 100.3E, geomagnetic latitude (MLAT): sporadic-E layers in both nighttime and day- 10.0S), Indonesia on 5 April 2011 from 13 to time conditions. Where available, neutral wind 22 UT (from 20 to 05 LT). These plasma bub- observations provide the complete electrody- bles were observed in 630-nm airglow images namic picture revealing an essential source of taken by using a highly-sensitive all-sky airglow free energy that both sets up the layers and imager. They propagated eastward with hori- drives them unstable. Electric field data from zontal velocities of about 100-120 m/s. Sim- the nighttime experiments reveal the presence ilar eastward-moving plasma bubbles were ob- of km-scale waves as well as well-defined pack- served in airglow images at Chiang Mai (18.8N, ets of broadband (10’s of meters to meters) 98.9E, MLAT: 8.9N), Thailand, which is a ge- irregularities. What is surprising is that in both omagnetic conjugate station of Kototabang. the nighttime and daytime experiments, neither Background thermospheric neutral winds were the large scale nor short scale waves appear also observed at both stations by using two to be distinctly organized by the sporadic-E Fabry-Perot interferometers (FPIs). Eastward density layer itself. The observations are dis- neutral-wind velocities observed by FPIs were cussed in the context of current theories re- about 70-130 m/s at Kototabang, and about garding sporadic-E layer generation and quasi- 50-90 m/s at Chiang Mai. The drift velocities periodic echoes. of plasma bubbles tend to be about 20 m/s larger than the eastward neutral velocities at TYPE: POSTER Kototabang. In the presentation, we discuss DATE: 2012-03-15 – 17:30 these results by considering the F-region dynamo effects.

P4.03 GEOMAGNETIC CONJUGATE TYPE: POSTER OBSERVATIONS OF PLASMA BUB- DATE: 2012-03-15 – 17:30 BLES AND THERMOSPHERIC NEU- TRAL WINDS AT EQUATORIAL LAT- ITUDES P4.SB1 VERTICAL COUPLING BE- TWEEN MESOPAUSE AND EQUATO- 1 1 Daisuke Fukushima , Kazuo Shiokawa , Yuichi RIAL IONOSPHERIC F REGION: A NEW 1 2 2 Otsuka , Michi Nishioka , Minoru Kubota , INSIGHT Takuya Tsugawa2, and Tsutomu Nagatsuma2 S. G. Sumod, T. K. Pant, and M. M. Hossain 1 Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Space Physics Laboratory, Vikram Sarabhai 2 National Institute of Information and Com- Space Centre, Trivandrum, India munications Technology, Japan This paper presents unique observations, The zonal propagation of plasma bubbles is illustrating the vertical coupling between the a manifestation of plasma and neutral coupling daytime mesopause and F region of the iono- in the equatorial thermosphere. The plasma sphere over a magnetic dip equatorial station bubbles show clear geomagnetic conjugacy [e.g. Thiruvananthapuram (8.5° N, 76.5°E, 0.5° N Otsuka et al., 2002]. However, the relation dip lat.) in India. For the ‘ﬁrst time’, it has between drift velocity of the plasma bubbles been shown that the temporal variations in the and neutral wind velocity was not quite inves- mean trends of the daytime mesopause temper- tigated at geomagnetic conjugate points. In ature (MPT), for geomagnetically quiet days

56 ISEA13 - 13th International Symposium on Equatorial Aeronomy spanning over different months during the years 3 MIT Haystack Observatory, Massachusetts 2005-2007, corroborate well with that of the Institute of Technology, MA, USA base height changes (h’F) of the ionospheric F region. The MPTs are measured using the Recent experimental and modeling studies unique Multi-Wavelength Dayglow Photometer have presented significant evidence that the while the h’Fs are derived using a co-located coupling between the neutral atmosphere and digital Ionosonde. However, there exist some the low-latitude ionospheric plasma is strongly characteristic time delays between these two, affected by sudden stratospheric warming which vary from 0 to 90 minutes. The ob- events. As stratospheric warming events are served time delays are attributed to the inter- driven by strong enhancement in high-latitude competing processes namely the diffusion and quasi-stationary planetary wave activity, these wave-dynamical processes, in modulating the studies raise many questions about communi- transport of atomic oxygen at these altitudes. cation pathways between the high-latitude neu- The results are new and significant, and pro- tral stratosphere and low-latitude ionosphere. vide a new insight into the chemical coupling We will discuss several mechanisms for the ubiquitous in the equatorial Mesosphere-Lower communication between these two regions and Thermosphere Ionosphere (MLTI) region. describe how they might be affected during SSW events . These include variations in ex- TYPE: POSTER citation of migrating and non-migrating tides, DATE: 2012-03-15 – 17:30 changes in the dynamics and temperature of the middle atmosphere that can affect upward propagation of tides, interaction between plan- P4.SB2 PLASMA NEUTRAL COUPLING etary waves and global tidal field, and mod- DURING SUDDEN STRATOSPHERIC ulation of ionospheric dynamo that in turn af- WARMING EVENTS fects the generation of the equatorial ionization Larisa Goncharenko1, Jorge Chau2, and Anthea anomaly. We will then postulate how changes Coster3 in these communication pathways due to SSW might contribute to the observed ionospheric 1 Haystack Observatory, Massachusetts Insti- changes. tute of Technology, Westford, Massachusetts, USA TYPE: POSTER 2 Radio Observatorio de Jicamarca, Instituto DATE: 2012-03-15 – 17:30 Geofísico del Perú, Lima, Perú

57 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 5

LOW AND MID LATITUDE AERONOMY AND ELECTRODYNAMICS

The main emphasis of session S5 is to focus on the behavior of electric ﬁelds and current systems on a global large scale during quiet times. The aim would be to provide a broad overview of how the ionosphere behaves during geomagnetic quiet times and weak solar activity and during the transition to a more intense solar activity period. Emphasis would be placed upon the description of the plasma component in regard to composition, density, temperature, and the background climatology of the neutral winds and ion drifts. Papers devoted to phenomenological features such as the equatorial ionization anomaly, pre-reversal enhancement, midnight temperature maximum/pressure bulge, and the electrodynamics at the terminators during quiet times and their relationships to the wind systems and tides would be welcomed.

Speciﬁc topics may be:

1. Studies of the electrodynamics of the ionosphere: description of recent results in composition, density, temperature, electric fields, ion drifts, transport, gravitational and magnetic field effects, mainly during quiet times or during the transition from quiet to storm time.

2. Ground-based in-situ measurements and related modeling.

3. Climatological studies (latitudinal, longitudinal, altitudinal, seasonal variation, solar conditions) and particular events relating to gravity wave perturbations and tidal variability.

Conveners: J. Meriwether, S. Gonzalez, and E. Pacheco

58 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - QUIET TIME VARIABILITY phenomenological and climatological features, IN THE ELECTRODYNAMICS OF THE including the behavior of field-aligned plasma LOW LATITUDE IONOSPHERE drifts. Temporal and spatial variations in the field-aligned ion drifts near the magnetic equa- Bela G. Fejer tor in the topside ionosphere are presented using observations from the Coupled Ion Neutral Utah State University, Logan, UT, USA Dynamics Investigation (CINDI) onboard the The low latitude ionosphere exhibits very Communications/Navigation Outage Forecast large variability over a broad range of tempo- System (C/NOFS) satellite. These observa- ral and spatial scales during geomagnetic quiet tions were obtained during the period of ex- times. Satellite measurements have recently tremely low solar activity present in 2008 and determined the season and longitude depen- 2009, allowing the seasonal, geographic, and dent climatology of the low latitude electrody- local time variations at solar minimum to re- namic plasma drifts, equatorial electrojet and veal the relative importance of the atmospheric plasma irregularities. Over the last few years, and ionospheric processes responsible for top- significant effort has been dedicated to the side field-aligned plasma drifts. study of short term (less than about a month) variability of low latitude electrodynamic pro- TYPE: ORAL cesses and plasma density driven by lower at- DATE: 2012-03-13 – 14:20 mospheric planetary and gravity waves, tides. These quiet time perturbations are particularly during sudden stratospheric warming events. LOW AND MID-LATITUDE CLIMA- In this presentation, we first review the clima- TOLOGY ASSESSMENT OF IONO- tology of low latitude electrodynamic plasma SPHERE/THERMOSPHERE MODELS drifts. Then, we use radar measurements from DURING SOLAR MINIMUM the Jicamarca Radio Observatory and satellite measurements to examine the main character- Barbara Emery1, David Anderson2, Jorge istics of the short term variability of low lat- Chau3, Anthea Coster4, John Emmert5, Mar- itude electrodynamic plasma drifts during low iangel Fedrizzi6, Larisa Goncharenko7, Ludger and high solar flux periods, and their effects on Scherliess8, Ja Soon Shim9, and Qian Wu1 the generation of equatorial plasma irregularities and spread F. 1 High Altitude Observatory, National Center TYPE: ORAL for Atmospheric Research, Boulder, CO, USA 2 DATE: 2012-03-13 – 14:00 CIRES, University of Colorado Boulder, CO, USA 3 Radio Observatorio de Jicamarca, Instituto CLIMATOLOGY OF TOPSIDE MAG- Geofísico del Perú, Lima, Perú NETIC FIELD-ALIGNED ION DRIFTS AT 4 MIT Haystack Observatory, Massachusetts SOLAR MINIMUM Institute of Technology, MA, USA 5 Naval Research Laboratory, USA Angeline Burrell, Roderick Heelis, and Russell 6 LASP, University of Colorado, Boulder, CO, Stoneback USA 7 University of Texas at Dallas, TX, USA Haystack Observatory, Massachusetts Insti- tute of Technology, Westford, Massachusetts, During solar minimum between solar cy- USA cles 23 and 24 the low levels of extreme ul- 8 Center for Atmospheric and Space Sciences, traviolet radiation led to a cool, contracted at- Utah State University, Logan, UT, USA mosphere. The affects of the neutral atmo- 9 University of Maryland, College Park, MD, sphere on the ionosphere have been observed in USA

59 ISEA13 - 13th International Symposium on Equatorial Aeronomy

The performance of Ionosphere/Thermosphere in 2007-2009. It is a critical issue that whether (IT) models at low and mid-latitudes during or not this deep solar minimum brought seri- the solar minimum period from March 2007 to ous influences on the Earth’s space environ- March 2008 is evaluated, with particular em- ment. In this study, we collected the iono- phasis on November 2007 to February 2008. grams recorded by a DPS ionosonde at Ji- For this study, the physical parameters selected camarca (12.0º S, 283.2º E) and manually are median values of the electron peak density scaled these data to retrieve F-layer parame- and the height of this peak from COSMIC ters and electron density profiles. A compar- LEO satellites, median total electron content ative study is performed to evaluate the dif- (TEC) from GPS satellites around 20,000 km ference in the equatorial ionosphere between observed at many ground stations, observed solar cycle 22/23 minimum (1996-1997) and and estimated vertical ion drifts at Jicamarca, recent deep minimum (2008-2009). Compared Peru, and global mean daily neutral densities to 1996-1997, the seasonal median values of from satellite drag analyses. Most of the IT the critical frequency of F2-layer (foF2) were models have been run at the Community Co- identified to be remarkably reduced during the ordinated Modeling Center (CCMC) at the deep solar minimum. It is the first time to Goddard Space Flight Center using appropriate find that lower values prevail at most times in geophysical inputs. Double resolution TIEGCM 2008-2009 in the F2-layer peak height (hmF2) model runs using SABER and TIDI tempera- and Chapman scale height (Hm). In contrast, ture and wind lower boundary conditions are the bottomside profile thickness (B0) in 2008- also evaluated. Climatological days are found 2009 shows higher values than that in 1996- using median values of observations and model 1997 at some daytime intervals, although it outputs, where medians reflect the quiet solar is also smaller during the rest times. Fur- minimum conditions. We examine 5 degree ge- thermore, the ionogram-retrieved electron den- ographic latitude and 5-25 degree geographic sity profiles demonstrate that the ionosphere in longitude bins located in 8 longitude swaths 2008-2009 is contracted strongly at altitudes with good ground TEC coverage. Percent de- above hmF2 and more perceptible in the after- viations of model values from data are evalu- noon hours. The decrease in Ne is strongest ated for low and middle latitudes as a function in September equinox and weakest in June sol- of day or night. stice. The reduction in solar EUV input from solar minimum to minimum mainly contributes TYPE: ORAL to the ionospheric responses, but the involved DATE: 2012-03-13 – 14:35 ionospheric processes are competed and variable in different time scales and played roles in the complicated variations in different sea- CHANGES IN THE EQUATORIAL IONO- sons and altitudes. Acknowledgments. The au- SPHERE OVER JICAMARCA DURING thors would like to thank B. W. Reinisch of the RECENT TWO SOLAR MINIMA Center for Atmospheric Research, University of Massachusetts Lowell for the ionogram data Libo Liu1, Weixing Wan2, Yiding Chen2, and of DIDBase. This research was supported by Huijun Le2 National Natural Science Foundation of China (40725014, 41074112, 41174137). 1 Beijing National Observatory of Space Envi- ronment, Institute of Geology and Geophysics, TYPE: ORAL Chinese Academy of Sciences, Beijing, China DATE: 2012-03-13 – 14:50 2 Institute of Geology and Geophysics, Chinese Academy of Sciences, China IONOSPHERIC VARIABILITY AT EQUA- The deep low minimum of solar cycle 23/24 TORIAL AND LOW LATITUDES DUR- has extremely extended and low solar activity ING PERIODS OF EXTREME SOLAR

60 ISEA13 - 13th International Symposium on Equatorial Aeronomy

QUIESCENCE and onboard LEO satellites. The day-today variabilities are described as a function Joei Sroten of longitude, latitude, local time, and seasons during periods of low solar flux condi- Boston University, MA, USA tions. The daytime TEC measurements show clear wavenumber-four structure and can per- The years 2008 and 2009 were periods of sist until post-midnight hours. The bottom extreme solar minimum conditions, a unique side E-region zonal wind observations, using occurrence for solar-terrestrial science in the the TIDI instrument onboard the TIMED satel- modern era. Observations made during these lite, indicate very good correlation with the years provide an opportunity to explore the density wavenumber-four structures. However, baseline state of the upper atmospheric sys- the meridional wind component near the bot- tem. In this study we examine the question tom side of the E region shows no correlation “Is this particular solar minimum merely a pro- with the density four cell pattern that we ob- longed period of solar quiescence, or a funda- serve from GPS TEC measurements. mentally different condition from previous solar minima?” We address the issue using a set TYPE: ORAL of ionosonde measurements from stations at DATE: 2012-03-13 – 15:20 equatorial and low latitudes. We examine the day-to-day variability of both the E-layer and the F2-layer, and compare their morphologies ON THE NOCTURNAL WESTWARD with concurrently measured parameters for so- DRIFTS OF THE LOW-LATITUDE lar and geomagnetic activity. With anticipated IONOSPHERE: AN OVERVIEW minimal coupling from above, does this period offer any special insights into the role(s) of cou- Jose Sobral pling from below? Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP, Brazil TYPE: ORAL DATE: 2012-03-13 – 15:05 The electrodynamical processes that lead to westward drifts of the nocturnal ionosphere at geomagnetic low latitudes are briefly re- THE DAY-TO-DAY LONGITUDINAL viewed here in the light of the theory for drifts VARIABILITY OF THE GLOBAL IONO- of the geomagnetic flux tubes. The zonal drifts SPHERIC DENSITY DISTRIBUTION AT during geomagnetically disturbed periods, in- LOW LATITUDES DURING LOW SOLAR cluding during the prompt global perturbations ACTIVITY are also considered here.

Edgardo Pacheco and Endawoke Yizengaw TYPE: ORAL DATE: 2012-03-13 – 15:35 Boston College, MA, USA

One important characteristic of longitudi- OBSERVATIONS OF THE VERTICAL nal variability of the ionosphere is the global AND ZONAL IONOSPHERIC PLASMA wavenumber-four signature. Recent investiga- DRIFT VELOCITIES, OBTAINED BY tions have focused mainly in its climatologi- IONOSONDES AND INCOHERENT cal pattern during daytime and evening sec- SCATTER RADAR AT THE BRAZILIAN tor. In this study, we investigate the day-to- AND PERUVIAN SECTORS OF GEO- day variability of the longitudinal structure of MAGNETIC LONGITUDE the ionospheric density for the ﬁrst time using the global total electron content (TEC) mea- Fernando C. P. Bertoni1, Mangalathayil Ali surements from GPS receivers on the ground Abdu2, Inez Staciarini Batista2, Jean-Pierre

61 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Raulin1, Bodo W. Reinisch3, Jose Sobral2, and 1 Helmholtz Centre Potsdam, German Re- Jonas Rodrigues De Souza2 search Centre for Geosciences, Germany 2 Technical University of Denmark, DTU 1 Centro de Radio Astronomía e As- Space, Denmark trofísica Mackenzie, Universidade Presbiteriana 3 Wuhan University, Department of Space Mackenzie, Brazil Physics, China 2 Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP, Brazil The temporal variations of the equatorial 3 University of Massachusetts Lowell, Center electrojet (EEJ) amplitude show clear relation for Atmospheric Research, Lowell, MA, USA to solar and lunar tides and to seasons. Like the EEJ, the formation of the equatorial ionisation The studies presented in this work show the anomaly (EIA) is driven by an eastward electric vertical and zonal drift velocity time series that ﬁeld. This study looks into the response of the were obtained in two periods of observation EIA strength to the lunar phase. A measure to in October and November, 2002, during the quantify the strength of the EIA is the crest-to- COPEX campaign. Three instruments provided trough ratio (CTR) of the ionisation anomaly. the data: two Digisondes (DPS-4 type), one lo- These data were obtained from CHAMP elec- cated at Cachimbo (9.5°S, 54.8°W, dip -4.25°), tron density readings during passes across the Brazil, other one located at the Jicamarca Ra- equatorial region. The CTR values are sorted dio Observatory (11.95°S, 76.87°W, dip 1°), by local time (LT), moon phase, solar cycle, where operates the third instrument used, the and season. On the dayside, between 09h Incoherent Scatter Radar. The values of the and 18h LT, CTR peaks as expected around vertical velocity measurements at the two lon- noon. This diurnal variation is modulated by gitude sectors, Jicamarca (JIC) and Cachimbo the lunar tide, giving largest amplitudes, as ex- (CAC), presented very reasonable correlation, pected, around new moon and full moon. The around sunset/evening hours, during moderate modulation of the CTR strength amounts to magnetic activity. Our results show that the about 10%. The lunar semi-diurnal wave ex- Digisonde drift velocity local time variation, for hibits largest CTR amplitudes around Decem- both the vertical and zonal components, follows ber solstice. During June solstice the CTRs the same behavioral trends as those from the are generally weaker. When comparing peri- ISR measurements, during most of the night- ods of high solar activity with solar minimum time hours, as well as part of the afternoon conditions, the overall CTR values are higher and sunrise hours. It motivates us to use the around maximum, but the lunar tidal signal is zonal velocity of the ionospheric plasma (driven clearer during low solar activity. The phase of by vertical dynamo electric ﬁelds) obtained by the semi-diurnal signal follows the moon age Digisondes, in order to further discuss the be- with a delay of 1.7h between moon phase and havior of zonal and vertical plasma drifts, for local time. Compared to the EEJ, the lunar quiescent and disturbed magnetic and solar ac- tidal signal of CTR appears 1-2 hours later in tivity periods. local time. Shortly after sunset the determination of the CTR tidal signal is disturbed by TYPE: ORAL equatorial plasma irregularities. DATE: 2012-03-13 – 15:50 TYPE: ORAL DATE: 2012-03-13 – 16:05

LUNAR SIGNALS IN THE VARIATIONS OF THE DAYTIME EQUATORIAL IONI- SOLAR FLUX BEHAVIOR OF THE SATION ANOMALY FROM CHAMP EQUATORIAL VERTICAL E×B DRIFT VELOCITIES OBTAINED FROM IONO- Patricia Ritter 1, Hermann Lühr1, Jaeheung GRAMS AT LONGITUDE 358.5OE SEC- Park1, Claudia Stolle2, and Chao Xiong3 TOR

62 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Oyedemi S. Oyekola THE OSCILLATION OF THE F RE- GION PEAK ALTITUDE IN THE EQUA- Private Individual, Etobicoke, Ontario, Canada TORIAL IONOSPHERE AT SUNRISE: EVIDENCE FOR AN INTERPLAY BE- TWEEN FIRST ORDER CHEMICAL EF- Ionosonde measurements made at Oua- FECTS AND SECOND ORDER ELEC- gadougou in Burkina Faso (12.4oN, 358.5oE; TRODYNAMICAL EFFECTS. dip latitude: 1.5oN) in the West African sector between January 1987 and December 1990 K. M. Ambili1, Jean-Pierre St-Maurice2, and are examined with the purpose of deriving solar Raj Kumar Choudhary1 flux behavior of the vertical plasma drifts in the 1 evening and nighttime equatorial ionosphere for Space Physics Laboratory, Trivandrum, India 2 quiet-condition. The results demonstrate that Institute for Space and Atmospheric Studies, low solar flux vertical drift values fluctuate sig- University of Saskatchewan, Canada nificantly than the high solar flux drift veloci- We have investigated the behavior of iono- ties between 1800 and 0600 local time for the sphere during sunrise using observations from three seasons, December solstice, equinoxes, a Digital Ionosonde (Digisonde) at Trivandrum, and June solstice periods. In addition, percent India. Of particular interest was an oscillation vertical drift variability varies between 97-162% in the height of the F region peak inferred from and 105-132% for low and high solar flux, re- a Digisonde measurements, with a sharp up and spectively. Also, low solar flux absolute drift down oscillation starting shortly before sunrise. variability is fairly larger than high solar flux However, the effect was not always seen, be- absolute variability. The rate of change in the ing often hidden by sporadic E layers or plasma evening pre-reversal velocity enhancement for density remnant from the previous night. Using unit change in F10.7 is considerably higher in a histogram-based technique we were however value during low solar flux year than moderate able to pull out a quantitative description of the and high solar flux periods. An outstanding fea- effect in spite of the sporadic screening effects. ture is that the evening velocity peak is strongly Since the vertical oscillation closely resembled anti-correlated with F10.7 at high solar activ- the oscillation of the well-known ‘pre-reversal ity years and worst for F10.7>200 units. On enhancement’ observed at sunset, we wanted to the other hand, analysis of corresponding post- investigate a possible electrodynamical origin sunset peaks in F2-layer, hmF2p show good for the observed sunrise oscillation. However, correlation relationship with solar flux values at using a one-dimensional model of the equato- low and moderate solar activity years, although rial ionosphere, we were able to show that the post-sunset peak in F2-layer peak (hmF2p) ver- sunrise oscillation phenomenon was mostly due sus F10.7 again exhibits low correlation val- to a quick descent of the shadow height dur- ues during high solar activity periods. We also ing sunrise, which created a downward motion show that the link between velocity peak Vzp of the F region peak as the plasma was re- and hmF2p exhibits large variations from low to building from high altitudes (600 km) at first, high solar activity years, with typical correlation subsequently steadily moving down to lower al- values of approximately 20-86%. The signifi- titudes as the density was building up. One cant ionospheric variation of vertical E×B drift point that became apparent with the simula- velocities observed during low solar flux con- tions was that the Digisonde could only probe ditions provide proof that ionospheric changes densities that were sufficiently high to accom- cannot be only ascribed to solar variability, but modate the lower Digisonde probing frequen- to non solar activity sources. cies. Another point was that we could also derive the second order corrections to chem- TYPE: ORAL istry that were produced by the vertical motion DATE: 2012-03-13 – 16:20 of the plasma introduced by the vertical plasma drift induced by zonal electric field. We showed

63 ISEA13 - 13th International Symposium on Equatorial Aeronomy in the process that the plasma motion was typ- Viswanathan Lakshmi Narayanan, Subrama- ically downward before sunrise but underwent a nian Gurubaran, Kaliappan Emperumal, and P. sharp upward transition two hours after sunrise. T. Patil

TYPE: ORAL DATE: 2012-03-13 – 16:35 Indian Institute of Geomagnetism, Navi Mum- bai, India

THE SÃO LUÍS 30 MHZ COHERENT SCATTER RADAR: ONE SOLAR CYCLE In the post sunset low latitude ionosphere, OF EQUATORIAL IONOSPHERIC MEA- the equatorial ionization anomaly (EIA) crest SUREMENTS move towards the equator as a result of change in the direction of the zonal electric field. This E. Shume1, Fabiano Rodrigues2, Esfhan Alam is referred to as reverse fountain effect. On Kherani3, and Eurico De Paula1 some nights, imaging observations of OI 630 nm thermospheric nightglow taken from low 1 Instituto Nacional de Pesquisas Espaciais - latitude Indian sector during deep solar mini- INPE, Sao Jose dos Campos, SP, Brazil mum period revealed southward movement of a 2 Atmospheric and Space Technology Research broad region of enhanced intensity. This could Associates, Boulder, CO, USA be seen in the meridional keograms and is inter- 3 Institut de Physique du Globe de Paris, preted as the equatorward passage of the EIA CNRS, Paris, France crest. In addition to the equatorward motion, The São Luís (2.33oS, 44.21oW), Brazil, the thickness of the crest region decreases as coherent scatter ionospheric radar has been in a result of recombination. This reduction in operation since December 2000. The addi- thickness is pronounced in the earlier part of the tion of two antenna sets in 2005 allowed the night and brings about an apparent drift that construction of in-beam radar images of scat- is added to the true equatorward drift of the tering structures. The radar has been rou- EIA crest. We have measured the equatorward tinely measuring equatorial electrojet irregular- drift speed of the EIA crest in the night time ities and 150-km echoes during day-time, and from the all-sky airglow images. The contribu- equatorial spread F at night. Using the radar tion from the apparent drift is also estimated data we have been investigating: storm-time and corrected. The drift speed varies widely be- behavior of equatorial electrojet irregularities, tween 28 m/s to 88 m/s with an average speed coupling between the lower- and upper atmo- of 52 m/s. A part of the variability might be sphere, drift characteristics, seasonal and solar due to variations in thermospheric meridional flux behavior of 150 km echoes, longitudinal wind. We have also estimated that the EIA variation of electric fields over the east and west crest reaches up to about 5 deg N dip latitude coasts of South America, large scale waves in in this solar epoch over Indian sector. Further, the bottom-side F region at the onset of equa- no noticeable differences are seen in the equatorial spread F, and night-time vertical coupling torward drift speeds obtained on quiet and dis- between the E and F regions. turbed days. The studies that concentrate on the evolution of EIA with the help of airglow ob- TYPE: ORAL servations are rare. In this preliminary work, we DATE: 2012-03-13 – 16:50 have attempted to study the reverse fountain effect and its variabilities by means of careful analysis of thermospheric airglow images. A STUDY ON THE NIGHT TIME EQUATORWARD MOVEMENT OF ION- IZATION ANOMALY USING THERMO- TYPE: ORAL SPHERIC AIRGLOW IMAGING TECH- DATE: 2012-03-15 – 10:30 NIQUE

64 ISEA13 - 13th International Symposium on Equatorial Aeronomy

RESULTS FROM THE FIRST TWO the neutral winds agree quite well. However, YEARS OF MEASUREMENTS OB- the EPB drift velocity is slower than that of TAINED FROM RENOIR IN BRAZIL the neutral winds in the early evening hours on several occasions suggesting the F-region dy- Jonathan J. Makela1, John Meriwether2, Ri- namo is not fully activated. We present several cardo Arlen Buriti3, Amauri F. Medeiros4, case studies of the results from RENOIR and Narayan P. Chapagain1, Y. Huang1, Daniel J. discuss their implications for understanding the Fisher1, and Brian J. Harding1 relationship between the neutrals and plasma, especially during periods showing the presence 1 University of Illinois at Urbana-Champaign, of EPBs. Urbana, IL USA 2 Physics and Astronomy, Clemson University, TYPE: ORAL Clemson, SC, USA DATE: 2012-03-15 – 10:45 3 Universidade Federal de Campina Grande - UFCG, Brazil 4 Departmento de Fisica, Universidade Federal THERMOSPHERIC WIND AND TEM- de Campina Grande, Campina Grande, PB, PERATURE CLIMATOLOGY FOR THE Brazil EQUATORIAL REGION: RESULTS AND COMPARISONS WITH THE WAM PRE- In 2009, a suite of instruments compos- DICTIONS FOR THE 2009-2011 PE- ing the Remote Equatorial Nighttime Obser- RIOD vatory of Ionospheric Regions (RENOIR) ex- John Meriwether1, Jonathan J. Makela2, Y. periment was installed in northeastern Brazil Huang2, Daniel J. Fisher2, Luis Navarro3, at Cajazeiras (6.86?S, 38.56?W) and Cariri Oscar Veliz3, Ricardo Arlen Buriti4, Amauri (7.38?S, 36.53?W). Here we primarily discuss F. Medeiros5, Rashid Akmaev6, Tim Fuller- results obtained from the optical instruments Rowell7, and Fei Wu7 in RENOIR, a wide-angle imaging system at Cajazeiras and a bi-static Fabry-Perot interfer- 1 Physics and Astronomy, Clemson University, ometer (FPI) array with one imaging FPI in- Clemson, SC, USA stalled at each site. When operating individ- 2 University of Illinois at Urbana-Champaign, ually, each FPI provides measurements of the Urbana, IL USA zonal or meridional neutral winds in the car- 3 Radio Observatorio de Jicamarca, Instituto dinal look directions. When operating in the Geofísico del Perú, Lima, Perú common volume mode, the FPI array provides 4 Universidade Federal de Campina Grande - collocated measurements of both the zonal and UFCG, Brazil meridional winds at two locations. Using data 5 Departmento de Fisica, Universidade Federal from the FPIs, we present a climatology of de Campina Grande, Campina Grande, PB, thermospheric neutral winds and temperatures Brazil obtained over two years, spanning from the 6 NOAA Space Weather Prediction Center, deep solar minimum to present. The imag- Boulder, CO, USA ing system provides observations of the spatio- 7 CIRES, University of Colorado Boulder, CO, dynamic properties of equatorial plasma bub- USA bles (EPB). Analysis of the structures in the images yields an estimation of the EPB mag- Fabry-Perot Interferometer (FPI) measure- netic zonal drift velocity, which can be com- ments of nighttime thermospheric winds and pared to the zonal neutral wind velocity mea- temperatures from multiple sites in South sured by the FPIs to investigate the coupling America have been obtained for the pe- between the neutrals and plasma during pas- riod of 2009-2011. These observations were sage of EPBs. In general, the simultaneous made from the Jicamarca Radio Observa- measurements of the EPB drift velocities and tory (11.96ºS, 76.86ºW) and Nazca (14.97°S,

65 ISEA13 - 13th International Symposium on Equatorial Aeronomy

74.89°W) in Peru and from Cariri (7.38°S, MESOSPHERIC TEMPERATURE VARI- 36.53°W) and Cajazeiras (6.89°S, 38.56°W) in ABILITY OVER THE ANDES MOUN- Brazil. A thermospheric wind and temperature TAINS (30 S) AND THE CENTRAL PA- climatology record covering the extended so- CIFIC OCEAN (20.8 N) lar minimum 2009-2011 period has been obtained for 24 months from the two Brazilian Michael Taylor1, Yucheng Zhao1, Pierre- FPI sites. The observations from the Peruvian Dominique Pautet1, Jonathan Pugmire1, Neal sector were more limited due to weather and Criddle1, Gary Swenson2, Steven Franke2, Alan logistics problems but good results were ob- Liu3, and James Hecht4 tained between April and September of 2011. 1 The analysis of the simultaneous results shows Utah State University, Logan, UT, USA 2 zonal winds that are 50 to 75% faster at Jica- University of Illinois at Urbana-Champaign, marca, as compared to the zonal wind speeds Urbana, IL USA 3 observed at the two Brazilian sites, with peak Embry Riddle Aeronautical University, Day- winds near 135 to 150 ms-1. This finding is tona Beach, FL, USA 4 consistent with increased plasma density in the The Aerospace Corporation, USA equatorial ionization anomaly over the Brazilian sites, which would produce increased ion drag. The Andes region provides an excellent nat- During the equinoctial period for both longitu- ural laboratory for investigating gravity wave in- dinal sectors, the meridional winds show similar fluences on the Upper Mesospheric and Lower behavior of generally weak winds with north- Thermospheric (MLT) dynamics with dominant ward surges of 50-75 ms-1 occurring at around gravity wave forcing expected from deep con- 22-23 LT and 04-05 LT. This similarity sug- vection during the summer months replaced gests the dominance of the winds by tidal wind by strong orographic forcing during the win- forcing from below and is supported by com- tertime, due to intense prevailing zonal winds parison with the WAM meridional wind night- blowing over the towering Andes mountain time behavior. The temperature observations range. In contrast, gravity wave forcing over show the appearance of the midnight temper- oceanic sites such as Hawaii, is expected to ature maximum (MTM) for both longitudinal be less intense and controlled year-round by sectors at almost the same local time (23-24 local weather disturbances. The Na lidar, me- LT) with similar peak amplitudes of 100-150 teor radar and airglow imaging instrument suite K. The Jicamarca temperatures are seen to be that comprised the very successful Maui-MALT slightly warmer by 25 to 50 K. These results are program was relocated from Hawaii (20.8°N) found to be reasonably consistent with the pre- to the new Andes Lidar Observatory (ALO) dictions of the WAM model, which successfully sited high in the Andes mountains (2,520 m) produced a MTM amplitude of much the same at Cerro Pachon, Chile (30.3°S, 70.7°W). As magnitude as is observed for all four seasons. part of this instrument set the Utah State Uni- Near the evening twilight period the observed versity (USU) Mesospheric Temperature Map- Brazilian temperatures are 25 to 35 K warmer per (MTM) was operated continuously from than the WAM predictions. This may be an in- Maui (2002-2005) and from ALO over the dication of a temperature enhancement related past two years (August 2009-to date) measur- to the tidal penetration of the thermosphere ing the nocturnal near infrared OH(6,2) band by tidal harmonics that is not captured in the and the O2(0,1) Atmospheric band intensity model and temperature perturbations to investigate a broad range of mesospheric wave forcings, TYPE: ORAL their seasonal variability and effects on the DATE: 2012-03-15 – 11:00 MLT environment. This presentation intro- duces new results from ALO using collaborative measurements of selected wave events, in- COMPARING GRAVITY WAVE AND cluding exceptionally large tidal perturbations

66 ISEA13 - 13th International Symposium on Equatorial Aeronomy

(70-100 K), unusual “jumps” in OH/O2 tem- decrease in the emission intensities during sum- perature possibly associated with wave break- mer months although, on an average, the so- ing, mesospheric bore events, and new evidence lar zenith angle is smaller in summers (when for an 90 day seasonal oscillation in meso- compared to winters) and the solar flux was spheric temperature. These are compared with high during that period. This is in contrast to our lower-latitude Maui-MALT measurements the predictions of the optical emission models from Hawaii to investigate differences in the as mentioned above. This apparently contro- wave forcing over the Andes Mountains and the versial observation is explained to be due to central pacific ocean. the compositional variability brought in by the heating of the upper atmosphere during the TYPE: ORAL summer season wherein there is a transport of DATE: 2012-03-15 – 11:15 neutral oxygen atoms to the winter hemisphere from the summer hemisphere. Evidences to this effect will be presented. This will be discussed EFFECT OF COMPOSITIONAL VARI- in the context of the significant potential of the ATIONS ON THE SEASONAL VARI- daytime optical emission measurements in the ABILITY IN THE OXYGEN DAYTIME investigations of upper atmospheric dynamics. OPTICAL EMISSIONS OVER MID- LATITUDES TYPE: ORAL DATE: 2012-03-15 – 11:30 Duggirala Pallamraju1, Fazlul I. Laskar1, P. A. V. S. Ganesh1, and Supriya Chakrabarti2 GENERAL BEHAVIOR AND INTRASEA- SONAL OSCILLATION OF TEM- 1 Physical Research Laboratory, Ahmedabad, PERATURE OBSERVED IN A LOW India LATITUDE MLT REGION BY ME- 2 Boston University, MA, USA TEOR RADAR, PHOTOMETER AND SABER/TIMED. Optical daytime airglow intensity variability provides us with a means of remote investiga- Ricardo Costa tions of the upper atmospheric behaviour. The daytime OI 630.0 nm (redline) airglow emis- Universidade Federal de Campina Grande - sion has three primary contributions, namely, UFCG, Brazil photoelectron impact on atomic oxygen, photo- dissociation of molecular oxygen, and disso- This work presents some results con- ciative recombination of ionic molecular oxy- cerning the temperature of the high atmo- gen. The redline emissions over mid-latitudes sphere observed by meteor radar, photometer typically show a diurnal pattern with a peak and SABER/TIMED over Cariri Observatory around noontime, especially during geomagnet- (7.4°S, 36.5°W). The data series, depending ically quiet conditions. The empirical model on the instrument, are from January 2004 to shows that the emissions vary as a function of December 2006. In general, the temperature solar flux and solar zenith angle. Both, larger observed by the meteor radar was the highest solar flux magnitudes and smaller solar zenith (mean of 225.4 K) while SABER was the lowest angles, contribute to a larger dayglow bright- one (190.1 K). On average, the difference was ness as the yield of excited oxygen atoms is around 17%. All instruments showed a strong greater as can be seen from the production semiannual oscillation with maxima on equinox mechanisms listed above. However, analysis of seasons and minima on solstices. Annual os- systematic observations of daytime optical OI cillation with amplitude of 50% of the semian- 630.0 nm emissions from a mid-latitude sta- nual one was also observed. Oscillations of 60- tion for over a year during 2003 – 04 showed a 70 day were observed on temperature obtained

67 ISEA13 - 13th International Symposium on Equatorial Aeronomy by the radar and SABER at 90km of altitude. optical data from both hemispheres and show We also included in this work a Lomb-Scargle measurements from geomagnetically conjugate analysis of zonal wind observed by the meteor locations. radar. This analysis also shows an oscillation of about 60 days on zonal wind. SABER tempera- TYPE: ORAL ture show a very pronounced 60 day oscillation DATE: 2012-03-15 – 12:00 above 105km. Initially these oscillations can not be attributed speciﬁcally to Kelvin waves INVITED - PROSPECTS FOR MODEL- because data from other sites on diﬀerent longi- ING AND FORECASTING TIDAL VARI- tude and latitude should also be analysed. The ABILITY AND LOW LATITUDE ELEC- temperatures observed by the meteor radar in TRODYNAMICS operation since July 2004 at Cariri are compared to OH(6,2) rotational temperatures and Tim Fuller-Rowell1, Rashid Akmaev2, Houjun SABER/TIMED for validation. Wang1, Fei Wu1, and Tzu-Wei Fang1

TYPE: ORAL 1 CIRES, University of Colorado Boulder, CO, DATE: 2012-03-15 – 11:45 USA 2 NOAA Space Weather Prediction Center, Boulder, CO, USA INVITED - LOW AND MIDLATITUDE THERMOSPHERE/IONOSPHERE PRO- Quiet-time electrodynamics at low latitude CESSES DURING EXTREME SOLAR is largely driven by E-region dynamo winds ACTIVITY CONDITIONS on the dayside, and E- and F-region dynamo winds on the nightside. The dayside winds are Carlos Martinis, JeffBaumgardner, Paul strongly forced by migrating and non-migrating Zablowski, Joei Wroten, and Michael Mendillo tides propagating upward from the lower atmo- Boston University, MA, USA sphere. These winds are quite variable from day-to-day, responding to changes in lower at- Processes observed near the crests of the mosphere circulation and interaction of the Equatorial Ionization Anomaly, between 10-20o tides with planetary waves and gravity waves mag lat, in general have a strong dependence as they propagate upwards into the lower ther- on solar and magnetic activities. We use all-sky mosphere. Whole atmosphere model numerical imaging systems that provide observations of simulation can now simulate the degree of vari- specific airglow emissions occurring in the ther- ability in the winds, and hence in the dayside mosphere. Information on the spatial 2-D, in electrodynamics at equatorial and low latitudes. latitude and longitude, and temporal variations These simulations, together with observations, of the processes can be obtained. The inclusion have also shown that during large-scale changes of line-of-sight GPS and in-situ satellite data in atmospheric circulation, such as during a complements and augments the analysis. We sudden stratospheric warming, there is not just look at how solar activity affects the occurrence an increase in variability, but that the increases of equatorial Spread-F (ESF), medium scale and decreases in vertical plasma drift are coher- traveling ionospheric disturbances (MSTIDs), ent. When combined with a data assimilation and midnight temperature maximum (MTM). system, the whole atmosphere model is able to A significant occurrence of MSTIDs at low lati- follow the dynamics of real events with high tudes is observed during low solar activity while fidelity, and the electrodynamic consequences. ESF is the dominant feature observed at high Since the lower atmosphere is predictable sev- solar activity. Solar activity seems not to have a eral days in advance, it opens up the prospect significant effect on MTM characteristics. The of also forecasting the consequences in the elec- effects of geomagnetic activity are also dis- trodynamics and the ionosphere. The challenge cussed. In addition to local observations we use remains if the upper atmosphere response to

68 ISEA13 - 13th International Symposium on Equatorial Aeronomy more modest changes in atmospheric circula- often associated with the forcing from the lower tion is also predictable, or if the signal becomes atmosphere, such as the longitudinal varia- lost in the natural variability. tions of the upward propagating tides. It has been difficult to separate out the relative con- TYPE: ORAL tribution between the lower atmospheric forc- DATE: 2012-03-15 – 14:00 ing and geomagnetic field variations when in- terpreting the observed signatures. Further- more, little effort has been made so far to eval- LISN MODEL-DATA ASSIMILATION RE- uate the different responses of the dynamics SULTS: SOLAR TIDES, LUNAR TIDES, and energetics to geomagnetic field variations AND OTHER DRIVERS between the ionosphere and plasmasphere in Vince Eccles a quantitative manner. In order to quantify the impact of the geomagnetic field variations Space Environment Corporation, Providence, in the ionosphere and plasmasphere, we have UT, USA developed the new Ionosphere-Plasmasphere- Electrodynamics (IPE) model. It consists of A physics-based model of the ionosphere a physics based model of an ionosphere and and electric fields is combined with data of ver- plasmasphere using the IGRF geomagnetic field tical TEC from GPS monitors, magnetic field configuration (APEX). Furthermore, the global variations from magnetometers, and F2 crit- ionospheric potential is solved self-consistently ical frequencies from ionosondes to best de- on the same grid. In this presentation, we will termine the drivers underlying the ionospheric make comparisons of the modeled properties variations. The basic neutral wind drivers of of the ionosphere and plasmasphere using the the solar and lunar tides provide a predictable full IGRF and a dipole geomagnetic field. Fur- variation. We examine the variations beyond thermore, we will quantify the impact of the these standard tides. As well as the difference geomagnetic field variations in observed signa- in longitude for these tidal winds. tures of the plasma densities and temperatures and electrodynamics. TYPE: ORAL DATE: 2012-03-15 – 14:20 TYPE: ORAL DATE: 2012-03-15 – 14:35

EVALUATING THE DYNAMIC AND EN- ERGETIC VARIATIONS OF THE IONO- INVESTIGATION OF THE EQUATO- SPHERE AND PLASMASPHERE ASSO- RIAL F3 LAYER CHARACTERISTICS CIATED WITH THE GEOMAGNETIC USING THE INTERCOSMOS-19 DATA FIELD VARIATIONS Alexander Karpachev1, Maxim Klimenko2, and Naomi Maruyama1, Phil Richards2, Tzu-Wei Vladimir Klimenko2 Fang1, Leslie Mayer1, Catalin Negrea1, Tim 1 Fuller-Rowell1, Arthur Richmond3, and Astrid Pushkov Institute of Terrestrial Magnetism, Maute3 Ionosphere and Radio Wave Propagation RAS, Troitsk, Moscow Region, Russia 1 CIRES, University of Colorado Boulder, CO, 2 West Department of Pushkov Institute of USA Terrestrial Magnetism, Ionosphere and Radio 2 George Mason University, VA, USA Wave Propagation RAS, Kaliningrad, Russia 3 High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA We studied the characteristics of the equatorial F3 layer during the period of high solar Longitudinal variations of the observed activity using the Intercosmos-19 (IK-19) top- ionospheric and plasmaspheric signatures are side sounding large data set (about 3600 passes

69 ISEA13 - 13th International Symposium on Equatorial Aeronomy across the equator). The F3 layer manifested AMERICAN SECTOR WITH LARGE itself as a cusp on the topside ionograms and LONGITUDINAL VARIATION IN MAG- identified as an ionization ledge, i.e. a local en- NETIC DECLINATION ANGLE hancement in electron density at heights over 1 1 the F2 layer maximum. IK-19 data show that Paulo Nogueira , Mangalathayil Ali Abdu , 1 this enhancement reaches 10–15% in the day- Jonas Rodrigues De Souza , Inez Staciarini 1 1 time, and 30% at night. We revealed diurnal, Batista , Esayas Shume , and Graham John 2 seasonal, latitudinal and longitudinal variations Bailey in the F3 layer occurrence probability (P), in 1 Instituto Nacional de Pesquisas Espaciais - maximum height and critical frequency of the INPE, Sao Jose dos Campos, SP, Brazil F3 layer, hmF3 and foF3. The F3 layer appears 2 University of Sheffield, England, UK together with the equatorial ionization anomaly (EIA) at around 08:00 LT. The F3 layer occur- We study the climatology of the Total Elec- rence probability in the LT interval from 12:00 tron Content (TEC) as observed by GPS re- LT until 22:00 LT averages 40–45% regardless ceivers over two equatorial stations in South of the season. The occurrence probability de- America with large difference in magnetic dec- creases towards morning, as a result the F3 lination angle, São Luís (2.33° S, 315.8ºE, dec- layer does not appear at 05:00–07:00 LT. Three lination: -19o) in Brazil and Arequipa (16.5°S, local peaks in P appear in diurnal variations for 288.5ºE, declination: 0.5o) in Peru. The TEC all seasons: at 12:00–14:00 LT, 17:00–18:00 LT variations for three solar activity levels (high, and 20:00–22:00 LT. All these peaks are con- moderate and low) have been analyzed. The nected with diurnal variations of the equatorial TEC values recorded over São Luís are larger vertical plasma drift. The F3 layer height in- than those over Arequipa. The rate of increase creases from 450 km in the early morning to of the TEC with intensification of the solar ac- 600–750 km in the afternoon and reaches the tivity is also different at the two sites, inde- maximum of 950 km at 21:00 LT. The F3 layer pendent of the season and local time. One is usually observed within a geomagnetic lati- of the main aims of the present work is to tude range from –10 deg to 10 deg around the investigate the longitudinal differences in the geomagnetic equator. This interval increases TEC values associated with the large variations up to +-15 deg when EIA is well-developed. in the magnetic declination angle using the The F3 layer and EIA crests exist near the same Sheffield University Plasmasphere Ionosphere geomagnetic field line. Longitudinal variations Model (SUPIM). The zonal electric field effects in P depend on the EIA longitudinal variations on the TEC magnitudes over the two South which are mainly determined by variations in America stations will be discussed. vertical plasma drift at geomagnetic equator. In addition we analyzed the IK-19 data dur- TYPE: ORAL ing 10 geomagnetic storm events with Kp > DATE: 2012-03-15 – 15:05 5. The F3 layer was generally absent during two storm events, was weakly manifested during five storms and was clearly seen only during EQUATORIAL-PRIMO (PROBLEMS RE- three storms. In this report, we also consider LATED TO IONOSPHERIC MODELS in detail the formation mechanism of the addi- AND OBSERVATIONS) tional layers in the equatorial ionosphere during 1 1 quiet and disturbed geomagnetic conditions. Tzu-Wei Fang , David Anderson , Tim Fuller- Rowell1, Rashid Akmaev2, Mihail Codrescu2, 1 3 TYPE: ORAL George Millward , Jan Sojka , Ludger 3 4 5 DATE: 2012-03-15 – 14:50 Scherliess , Vince Eccles , John Retterer , Joseph Huba6, G. Joyce7, Arthur Richmond8, Astrid Maute8, GeoffCrowley9, and Aaron EQUATORIAL TEC OVER SOUTH Ridley10

70 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 CIRES, University of Colorado Boulder, CO, to have fair comparisons, we assume the same USA ion-neutral collision frequency and set F10.7 to 2 NOAA Space Weather Prediction Center, 120. All the models are run under geomagnetic Boulder, CO, USA quiet conditions in equinox. For non-coupled 3 Center for Atmospheric and Space Sciences, models, diurnal variation of electron density at Utah State University, Logan, UT, USA Jicamarca and Asia longitudes at equatorial re- 4 Space Environment Corporation, Providence, gion are compared. Model results with only UT, USA neutral wind or electric field will also be pre- 5 Boston College, MA, USA sented to identify the causes of differences. For 6 Plasma Physics Division, Naval Research Lab- coupled models, the diurnal variation of elec- oratory, USA tron density in E- and F-region, neutral wind 7 Icarus Research, Inc., Bethesda, MD, USA and electrodynamics are compared. We will 8 High Altitude Observatory, National Center present these results, discuss the differences, for Atmospheric Research, Boulder, CO, USA and describe our vision of the way forward for 9 Atmospheric and Space Technology Research Equatorial-PRIMO. Associates, Boulder, CO, USA 10 Center for Space Environment Modeling, TYPE: ORAL University of Michigan, Ann Arbor, MI, USA DATE: 2012-03-15 – 15:20

We do not fully understand all the relevant physics of the equatorial ionosphere, so DC AND STRUCTURED ELECTRIC that current models do not completely agree FIELDS OBSERVED ON THE C/NOFS with each other and are not able to accu- SATELLITE AND THEIR ASSOCIATION rately reproduce observations. To understand WITH LONGITUDE, PLASMA DEN- the strengths and the limitations of theoretical, SITY, AND SOLAR ACTIVITY time-dependent, low-latitude ionospheric models in representing observed ionospheric struc- Robert Pfaff, Henry Freudenreich, Doug Row- ture and variability and to better understand land, and JeffKlenzing the underlying ionospheric physics and develop improved models, we initiated a multi-year NASA Goddard Space Flight Center, Green- Equatorial-PRIMO workshop at the CEDAR belt, MD, USA meeting this year. Two sets of ionosphere- plasmasphere models are participated: non self- Observations of DC electric fields and as- consistent models including Ionospheric Fore- sociated E x B plasma drifts gathered by the cast Model (IFM), Ionosphere-Plasmasphere Vector Electric Field Investigation (VEFI) on Model (IPM), Low Latitude Ionosphere Sec- the Air Force Communication/Navigation Out- tor Model (LLIONS), Physically Based Model age Forecasting System (C/NOFS) satellite are (PBMOD), Global Ionosphere and Plasma- presented. We show statistical averages of the sphere (GIP), SAMI2 is Another Model of vector fields and resulting E x B plasma flows the Ionosphere (SAMI2) and self-consistent for the first three years of operations as a func- models including SAMI3 is Also a Model tion of season, longitude, local time, and F10.7 of the Ionosphere (SAMI3), Thermosphere- conditions. Magnetic field data from the VEFI Ionosphere-Electrodynamics general circulation science magnetometer are used to compute the model (TIE-GCM), Thermosphere-Ionosphere- plasma flows. Although typically displaying Mesosphere-Electrodynamics general circula- eastward and outward-directed fields during the tion model (TIME-GCM), Global Ionosphere- day and westward and downward-directed fields Thermosphere Model (GITM), the Coupled at night, the data from DC electric field de- Thermosphere Ionosphere Plasmasphere Elec- tector often reveal variations from this pattern trodynamics (CTIPe), Integrated Dynamics that depend on longitude, solar activity, and through Earth’s Atmosphere (IDEA). In order plasma density. Clear “wave-4” tidal effects in

71 ISEA13 - 13th International Symposium on Equatorial Aeronomy both electric field components have been de- (EIA). These signatures are interpreted as be- tected and will be presented. Zonal plasma ing due to very rapid (several hundred meters drifts show a marked variation with solar ac- per second) meridional winds associated with tivity and may be used as a proxy for neutral the equatorial ion fountain at dusk. The winds winds at night. Evidence for pre-reversal en- are shown to be consistent with a picture of hancements in the meridional drifts that de- the EIA at dusk developed from DE-2 measure- pend on solar activity is present for some lon- ments and discussed as the Equatorial Temper- gitudes, and are corroborated by clear evidence ature and Wind Anomaly. The present mea- in the plasma density data that the spacecraft surements show how these winds depend on journeyed below the F-peak during evenings altitude. Furthermore, the wind structure ex- when the rise in the ionosphere is most pro- hibits a set of convection rolls that extends to nounced. In addition to DC electric fields, the high latitudes and is thus a form of coupling data reveal considerable electric field structures from low latitude to high latitude. at large scales ( 100’s of km) that are usually confined to the nightside. Although such elec- TYPE: ORAL tric field structures are typically associated with DATE: 2012-03-15 – 16:05 plasma density depletions and structures, what is surprising is the number of cases in which large amplitude, structured DC electric fields NEW MEASUREMENT OF THE EF- are observed without a significant plasma den- FECTS OF ION-NEUTRAL COLLISIONS sity counterpart structure, including their ap- IN THE E-REGION OVER ARECIBO pearance at times when the ambient plasma density appears relatively quiescent. We in- Johathan Fentzke1, Michael Sulzer2, and Sixto vestigate the mapping of structured electric Gonzalez2 fields along magnetic field lines from distant 1 locations and consider tropospheric thunder- Applied Physics Laboratory, John Hopkins storm sources to explain some of the observa- University, MD, USA 2 tions. The dependence of the structuring on Arecibo Observatory, Puerto Rico season and solar activity will be reported and discussed. Recently we have implemented a new experimental mode using the 430 MHz Arecibo TYPE: ORAL transmitter in which a coded long pulse is in- DATE: 2012-03-15 – 15:50 terleaved with a pulse-to-pulse scheme to provide an enhanced resolution in the lower E- region. The purpose of this experiment is to MERIDIONAL WINDS IN THE EQUA- measure the effects of ion-neutral collisions on TORIAL IONIZATION ANOMALY OB- the incoherent scatter spectrum and to im- SERVED BY THE STREAK MISSION prove the understanding of the process that modifies the spectrum in the lower E-region James Clemmons and Richard Walterscheid of the ionosphere between approximately 85 - 150 km under the assumption of Brown- The Aerospace Corporation, USA ian [Chandrasekhar, 1943], Bhatnagar-Gross- Krook (BGK) [Bhatnagar et al., 1954], and New analyses of thermospheric measure- Hard-Sphere collisions [Chapman and Cowl- ments from the ionization gauge on the Streak ing, 1970] in the absence of magnetic field mission are presented and discussed. These influences, for operating frequencies represen- measurements, returned from the dusk bot- tative of the chain of NSF-sponsored incoher- tomside ionospheric F-layer, show strong sig- ent scatter radars (ISRs), which range from natures in the neutral gas impressed through 50 MHz - 1290 MHz. Also, we extend the the action of the equatorial ionization anomaly computationally limited modeling examples in

72 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Hagfors and Brockelman [1971] of this phe- in the seismic active periods. At the analy- nomena and compare our updated modeling sis of these numerical experiments the forma- results to the measured experimental results tion mechanisms of such local zonal electric from Summer 2011. We show that the origi- fields were not discussed. The formation mech- nal non-dimensionalized examples from Hagfors anism of the zonal electric field over earthquake and Brockelman [1971] were representative of preparation area was proposed recently. The spectra at approximately 95 km, 105 km, and analysis of the basic hypotheses of lithosphere- 150 km. Additionally; we discuss the potential atmosphere-ionosphere coupling shows that the impact of these new measurements on the de- large-scale seismo-ionospheric anomalies some termination of various ionospheric parameters. days prior to strong earthquakes located in immediate proximity from earthquake epicentre TYPE: ORAL can be explain only by the small-scale IGWs DATE: 2012-03-15 – 16:20 and/or seismogenic electric fields in the Earth’s ionosphere. In this study, we present the results of GSM TIP model runs to reproduce P5.01 LOW-LATITUDE IONOSPHERIC the observed changes in the ionosphere prior to EFFECTS BEFORE STRONG EARTH- earthquakes: Koyna (11.12.1967), New Guinea QUAKES: THEORY, MODEL RESULTS, (16.07.1980), Sumatra (26.12.2004), Peru NEW ASPECTS AND RECENT AD- (25.09.2005), and Wenchuan (12.05.2008). VANCES The obtained results confirm the proposed formation mechanisms of low-latitude seismo- ionospheric effects by the seismogenic vertical Maxim Klimenko1, Vladimir Klimenko1, and electric field penetrated from the atmosphere Sergey Pulinets2 into the ionosphere. The obtained results may

1 also help to reveal other ionospheric variations West Department of Pushkov Institute of before strong earthquakes not considered ear- Terrestrial Magnetism, Ionosphere and Radio lier, for example, equatorial electrojet (EEJ) Wave Propagation RAS, Kaliningrad, Russia and the F3 layer variations. 2 Fedorov Institute of Applied Geophysics, Moscow, Russia; Institute of Space Research, POSTER RAS, Moscow, Russia TYPE: DATE: 2012-03-13 – 17:35 Recent studies was shown that the ionospheric eﬀects before strong near-equatorial earthquakes might be in the form of equatorial P5.02 WHISTLER WAVE-INDUCED ionization anomaly (EIA) strengthening (deep- IONOSPHERIC PLASMA TURBU- ening and widening electron density trough over LENCE: SOURCE MECHANISMS AND the geomagnetic equator and displacement of REMOTE SENSING EIA crests away from the equator) or EIA weak- 1 2 ening (the EIA trough decreasing and equator- Min-Chang Lee , Rezy Pradipta , Mike 3 3 3 ward displacement of the EIA crests). The ex- Sulzer , Sixto Gonzalez , Craig Tepley , Nestor 3 2 planation problems of possible physical mech- Aponte , Maria De Soria-Santacruz Pich , 2 2 anisms formation of the seismo-ionospheric ef- Rui Hu , Manuel Martinez-Sanchez , Kangping 1 1 1 fects are under discussion now. Earlier in the Hu , Lisa Rooker , Lindsey Whitehurst , and 1 numerical experiments with used the Global Aydan Uyar Self-consistent Model of the Thermosphere, Ionosphere, Protonosphere (GSM TIP) it has 1 Boston University, MA, USA been shown that the local disturbances of the 2 Massachusetts Institute of Technology, MA, zonal electric ﬁelds allow reproducing the mor- USA phology of ionospheric disturbances observed 3 Arecibo Observatory, Puerto Rico

73 ISEA13 - 13th International Symposium on Equatorial Aeronomy

We present a tutorial lecture to report a se- waves into the ionosphere, we rely on naturally ries of experiments conducted at Arecibo Ob- occurring spread F irregularities to serve as the servatory, in the past several years, aimed at the ionospheric ducts. However, artificial waveg- investigation of 40.75 kHz whistler wave inter- uides can be favorably generated by HF heater actions with ionospheric plasmas and the inner waves, as demonstrated in our earlier Arecibo radiation belts at L = 1.35. The whistler waves experiments [Lee et al., 1998] and further con- are launched from a Naval transmitter (code- firmed in our recent Gakona experiments at named NAU) operating in Aguadilla, Puerto HAARP [Cohen et al., 2010]. The newly con- Rico at the frequency and power of 40.75 kHz structed Arecibo HF heater will be employed and 100 kilowatt, respectively. Arecibo radio in our future experiments for further study of and optical instruments [i.e., 430 MHz radar, whistler wave interactions with the ionosphere CADI, Fabry-Perot Interferometer] in conjunc- and the magnetosphere/radiation belts as well tion with All Sky Imaging System and GeoMag- as the whistler wave conjugate propagation be- netic Observatory System have been used to tween Arecibo and Puerto Madryn, Argentina monitor the background ionospheric conditions [Starks and Lee, 1999; Starks et al., 2002; Lee and detect induced ionospheric plasma effects. et al., 2006 Arecibo Workshop]. An intriguing phenomenon known as “explosive spread F” motivates this work, which was TYPE: POSTER first reported by Woodman and LaHoz [1976] DATE: 2012-03-13 – 17:35 in experiments carried out at Jacamarca Ra- dio Observatory. It has been associated with P5.04 CLIMATOLOGY DURING A LOW the occurrence of lightning [Woodman and La- SOLAR ACTIVITY AND ENHANCE- Hoz, 1976; Woodman et al., 1984]. A charac- MENTS IN THE CRITICAL FREQUENCY teristic feature of this phenomenon is a train FOF2 OVER CYPRUS IN THE ABSENCE of short-lived, backscatter radar echoes with OF PRONOUNCED GEOMAGNETIC AC- a period of 6 sec, which occurred at two TIVITY altitudes in F region. A theory was subsequently presented by Liao et al.[1989], based Vryonides Photos1, Economou Lefteris2, and on a four-wave interaction process [Lee and Haris Haralambous1 Kuo, 1984], to interpret that “explosive spread F” was caused by lightning-induced whistler 1 Frederick University, Cyprus waves. It was suggested that the Jicamarca 2 Intercollege, Cyprus 50 MHz radar detected the whistler wave- excited field-aligned, zero-frequency modes and A new ionospheric station was established lower hybrid waves. In our Arecibo experi- three years ago in Nicosia (Cyprus) to initi- ments, we depend on NAU-launched, rather ate ionospheric research on the island. As the than lightning-induced, whistler waves for the Nicosia station is the lowest-latitude operating controlled study of aforementioned four-wave station in Europe the deployment of a DPS-4D interaction process [Labno et al., 2007], direct (digisonde) is considered very beneficial to the acceleration of ionospheric electrons by whistler ionospheric scientific community, taking into waves, and triggered precipitation of energetic account the lack of adequate scientific infras- electrons from the radiation belts [Pradipta et tructure, especially at low latitudes of the Euro- al., 2007]. Radar and optical measurements pean sector, for continuous ionospheric moni- can distinguish wave-wave and wave-particle in- toring. Its operation will contribute to inter- teraction processes occurring at different alti- national networks for ionospheric nowcasting tudes. Electron acceleration by different mech- and forecasting and to the validation of iono- anisms can be verified from the radar mea- spheric models in the eastern Mediterranean re- surements of plasma lines. To facilitate the gion. In this study we present the climatology coupling of NAU-launched 40.75 kHz whistler of the critical frequency of the F2-region during two years of operation (2009-2010) of the

74 ISEA13 - 13th International Symposium on Equatorial Aeronomy ionospheric station based on manually scaled TYPE: POSTER foF2 values and cases during the three year DATE: 2012-03-13 – 17:35 operation of the station where signiﬁcant enhancements in the critical frequency of the F2 layer foF2 were observed in the absence of pro- P5.08 ROCKET OBSERVATIONS OF nounced geomagnetic activity. ELECTRON TEMPERATURE AND EN- ERGY DISTRIBUTION IN THE LOWER TYPE: POSTER F-REGION PRIOR TO THE ONSET OF DATE: 2012-03-13 – 17:35 EQUATORIAL PLASMA BUBBLES

Polinaya Muralikrishna1 and Francisco Carlos P5.07 RADAR AND OPTICAL OB- De Meneses2 SERVATIONS OF SUDDEN ZONAL 1 Instituto Nacional de Pesquisas Espaciais - WIND DECREASE IN THE EQUATO- INPE, Sao Jose dos Campos, SP, Brazil RIAL ZONAL NEUTRAL WIND 2 State Key Laboratory of Space Weather, Cen- John Meriwether1, Andrew Gerrard2, Jonathan ter for Space Science and Applied Research J. Makela3, Daniel J. Fisher3, Luis Navarro4, (CSSAR), Chinese Academy of Sciences, Bei- Oscar Veliz4, and Ricardo Arlen Buriti5 jing, China

1 Physics and Astronomy, Clemson University, Height profiles of the ionospheric elec- Clemson, SC, USA tron density and temperature were made from 2 New Jersey Institute of Technology, The Cen- Brazil on different occasions under differ- ter for Solar-Terrestrial Research, NJ, USA ent ionospheric conditions. During one of 3 University of Illinois at Urbana-Champaign, the launches the rocket passed through well- Urbana, IL USA developed plasma bubbles on both upleg and 4 Radio Observatorio de Jicamarca, Instituto downleg. During the second launch the iono- Geofísico del Perú, Lima, Perú spheric F-region did not show the presence 5 Universidade Federal de Campina Grande - of prominent plasma bubbles. During the UFCG, Brazil third launch the rocket on its upleg passed through an F-region without plasma bubbles During the CORRER summer campaign in while on its downleg it passed through an F- August, 2011, the Fabry-Perot interferometer region that showed a large number of well- located at Jicamarca, Peru, and also at Huan- developed plasma bubbles. Electron temper- cayo, Peru, observed simultaneously on 9-10 atures were estimated by applying sweep po- and 10-11 August an interesting event in which tentials to Langmuir probes. During the first the zonal neutral wind decreased within 20-30 and second launches the electron temperatures minutes from the nominal speed of 125 ms-1 estimated were comparable to those given by eastward to nearly zero. This reduction lasted models. But during the third launch the elec- for perhaps 30 minutes and then the zonal wind tron temperatures estimated showed abnor- speed recovered to its nominal level prior to the mally high values of more than 3000 deg. K event. The zonal ion drift observed by the Ji- in the lower F- region only on the rocket upleg. camarca incoherent scatter radar also showed a The maximum electron temperature observed marked reduction in speed. The electron den- above the F-peak was only about 700 deg. sity profiles showed no marked change during K. The region below the base of the F-region this period but there was indication of the ex- seems to be associated with very large elec- istence of the bottom side Spread F. The ques- tron temperatures just before the development tion arises as to what might have caused such a of plasma bubbles. An attempt is made here marked change in the zonal wind as there was to get the electron energy distribution func- no indication of marked modulation that would tion (EEDF) from the second derivative of the be characteristic of gravity wave activity. current-voltage characteristic curves.

75 ISEA13 - 13th International Symposium on Equatorial Aeronomy

TYPE: POSTER One of the advantages of using ISR data is DATE: 2012-03-13 – 17:35 the possibility of exploring the altitude dependence of the MTM. Preliminary results indicate that between 250 and 400 km signiﬁcant vari- P5.09 MTM CHARACTERISTICS FROM ation of MTM characteristics is observed. We ARECIBO INCOHERENT SCATTER also discuss ongoing studies that include the RADAR use of Millstone Hill Incoherent Scatter Radar data, in particular low elevation angle runs that Dustin Hickey, Carlos Martinis, Ashley Wright, allow the determination of thermospheric Ti and William Oliver near 25-30o GLAT.

Boston University, MA, USA TYPE: POSTER DATE: 2012-03-13 – 17:35 We conduct a comprehensive study of the midnight temperature maximum (MTM) using data from the Arecibo Incoherent Scat- P5.10 COMPARISON OF GLOBAL ter Radar from 1966 to 2006. The MTM is MODEL AND IONOSONDE VERTI- a local maximum in the neutral temperature CAL DRIFTS OBSERVATIONS IN THE around midnight. A direct consequence of the POSTSUNSET EQUATORIAL IONO- MTM is the downward descent of the F-region SPHERE plasma, termed ‘midnight collapse’ or ‘midnight descent’. The absence of any plasma pro- Oyedemi S. Oyekola duction by absorption of EUV radiation during the night allows the electron and ion tempera- Private Individual, Etobicoke, Ontario, Canada tures to relax to the neutral temperature in the thermosphere. Thus variations in the nighttime In this paper, vertical plasma drift veloc- plasma temperatures Te and Ti, determined by ities deduced from ionosonde measurements ISR techniques, should reflect variations in the made at the Ibadan Radio Observatory (7.4oN, neutral temperature Tn. We characterize the 3.9oE, dip latitude 2.3oS ), in Nigeria, between MTM in terms of amplitude, time of occurrence January and December 1958 during Interna- and width. These parameters are obtained by tional Geophysical Year, are compared with fitting the radar data with a function that takes the empirical IRI-2007 model predictions in the into account diurnal, semidiurnal and terdiur- postsunset equatorial F region ionosphere over nal components. Under the hypothesis that the West African sector. The analysis covers geo- MTM is related to the amplification of the ter- magnetically quiet-day and very high solar ac- diurnal wave, a Gaussian window is included in tivity periods. We explore the relationship be- the fitting. This allows an automatic determi- tween ionosonde drifts and the Scherliess-Fejer nation of the time of occurrence, temporal du- climatological E×B drift velocity curves be- ration, and amplitude of the MTM observed. tween 1700 and 2200 local time. On average, our qualitative and quantitative compar- The ISR data contains information from isons are reasonably good. The results of the multiple heights ranging from about 100 to 600 study also indicate that in the seasonal vari- km. This study focuses on altitudes near 300 ation of the F region vertical drift variabil- km, the typical height of MTM observations ity, the absolute variability is smaller in June from Fabry Perot Interferometers. More than solstitial months than in equinoxes and De- 200 nights are used in this study with approx- cember solstice months. In addition, month- imately 80% of the nights showing an MTM to-month variability of the vertical drifts is with typical amplitudes ranging between 20 and higher in simulation results, about 16-40 m/s 100 K. A seasonal dependence on the local time than in ionosonde-inferred drifts, 9-23 m/s. of occurrence and amplitude is observed. The evening prereversal enhancement (PRE) of

76 ISEA13 - 13th International Symposium on Equatorial Aeronomy the vertical plasma drift signifies large month- and S Vijaya Bhaskara Rao1 1Department of to-month variations with amplitudes of about Physics, Sri Venkateswara University, Tirupati, 20-45 m/s and 19-50 m/s, respectively, for India 2National Atmospheric Research Labora- ionosonde and IRI model. The magnitudes of tory, Gadanki, India the modeled evening peak velocities are consistently larger than the values of ionosonde In this paper we present and discuss the re- evening PRE of the upward drift velocities sults on F3 layer based on observations made up to 40%, except for February and Novem- from Gadanki and Sriharikota, both are located ber. We demonstrate that the evening reversal in southern India with same latitude but lon- times are roughly comparable during December gitudinally separated by 100 km. Importantly solstice and September equinox, while March we present for the first time two important as- equinox and June solstice (except August) re- pects of the F3 layers: (1) the variability of versal times exhibits notable significant differ- the F3 layer properties during extreme low so- ences. The occurrence local time of the peak lar activity (LSA) period and compare them PRE E×B drift velocity for both Ibadan and with those observed during the high solar activ- model essentially show up at 1900 LT, apart ity (HSA) period, and (2) the variation in the from March and November that occurs late F3 layer property with varied ExB values. The and earlier, in that order. We also show that ExB drifts were estimated using the daytime the rate of change of the peak postsunset east- 150-km echoes observed simultaneously using ward drifts for unit change in solar flux F10.7 is the Gadanki MST radar. The results show approximately 0.16 m/s and 0.54 m/s, respec- that while the occurrence rate of F3 layer is tively, for Ibadan ionosonde drifts and IRI-2007 nearly equal in summer and September equinox model predictions. This study demonstrates of both HSA and LSA periods with occurrence that realistic ionosonde-inferred E×B drifts can percentage close to 100 %, in March equinox be obtained on quiet days in the West African and winter the occurrence rate is lower during sector and relates to the occurrence of small LSA period than in the HSA period. Also, in scale plasma irregularities that occurs just after summer the layer occurs earlier and last longer sunset. Our observations are useful for validat- than in other seasons. The critical frequency ing the IRI model representations of the vertical of the F3 layer is in the range of 5-7 MHz dur- drift velocities in the equatorial ionosphere. ing LSA whereas it is 10-13 MHz during HSA, which is 5-6 MHz higher than those observed TYPE: POSTER during LSA. The virtual height of the F3 layer is DATE: 2012-03-13 – 17:35 found to be 100 km higher both in summer and winter of HSA period (600-700 km) than those of LSA period (500-600 km). During equinox, P5.12 SOLAR FLUX AND EXB DEPEN- however, it is found to be 100 km higher in DENT FEATURES OF F3 LAYER OB- LSA period (600-700 km) than in HSA period SERVED FROM INDIAN LOW LATI- (500-550 km). We also found that the height TUDE STATIONS of the F3 layer correlates extremely well with the ExB drift indicating the dominant role of Pavan Chaitanya Peddapati1, Amit K. Patra2, zonal electric field in determining the height and S. Vijaya Bhaskara Rao1 of the F3 layer due to the close proximity of Gadanki/Sriharikota to the magnetic equator, 1 Sri Venkateswara University, India where the role of meridional neutral wind in 2 National Atmospheric Research Laboratory, layer movement is possibly not so significant. Gadanki, India These results are discussed in the light of current understanding on F3 layer. Solar flux and ExB dependent features of F3 layer observed from Indian low latitude TYPE: POSTER stations P Pavan Chaitanya1, A K Patra2, DATE: 2012-03-13 – 17:35

77 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Angela M. Santos, Mangalathayil Ali Abdu, Jose Sobral, Paulo Nogueira, and Claudia Can- P5.13 A STUDY OF DIFFERENT BLAN- dido KETING ES LAYERS DURING THE SO- Instituto Nacional de Pesquisas Espaciais - LAR CYCLE 23 INPE, Sao Jose dos Campos, SP, Brazil

Laysa Cristina Araújo Resende, Clezio Mar- In this work we study the dependence of the cos De Nardin, Inez Staciarini Batista, Juliano evening F region vertical peak velocity magni- Moro, and Lais Maria Guizelli tude (Vzp) which is associated to the prereversal enhancement in the zonal electric field Instituto Nacional de Pesquisas Espaciais - (PRE), as a function of solar flux index F10.7 INPE, Sao Jose dos Campos, SP, Brazil and EUV flux over the Brazilian region. The Vzp magnitude calculated from Digisonde data We investigate the behavior of blanket- from Fortaleza (3.9°S, 38.45°W) and São Luís ing frequency (fbEs) measured by a digi- (2.33° S, 44.2°W) during October, November tal ionosonde over São Luís, Brazil (2.33°S, and December from 2001 up to 2009 for quiet 44.2°W, dip: -4.5°), associated with different and disturbed days have been analyzed. The types of Es, according to the magnetic distur- results show that the Vzp is strongly dependent bance level and, in relation to the phase of on the F10.7 and it presents higher magnitudes strong magnetic storms that occured during the in November than in the other months for all solar cycle 23. Our preliminary results showed F10.7 levels both at São Luís and Fortaleza. It that there are expressive changes in the fbEs was also observed that the correlation between characterized by occurrence of peaks that ex- the Vzp and F10.7 parameters shows better re- ceeds the ambient background values, mainly sults during low solar activity. Recent works during the recovery phase of strong magnetic have reported a better correlation of daily val- storms. These peaks are associated to the pres- ues of mean TEC with EUV rather than with ence of blanketing Es types, which are not the F10.7. The objective of the present study is to common Es at the dip equator but replaced improve our understanding of the Vzp correla- the Esq, a non-blanketing layer observed in tion with solar activity intensity, which will be ionograms due the plasma irregularities in the potentially of help for the PRE and plasma bub- equatorial electrojet electric field. Therefore, ble forecasting. For that purpose we are verify- we suppose the wind shear mechanism is taking whether or not the dependence of the Vzp ing place at latitudes close to the dip equa- with the solar EUV is similar to that with F10.7 tor, where it is not supposed to operate ef- considering that the electric field responsible ficiently. The results are discussed in terms for the vertical drift is produced basically by of the statistics of the abnormal enhancement thermospheric winds which in turn are closely taking into account the magnetic disturbance associated to the EUV index. The main focus level and phase of the magnetic storm, when of this investigation therefore is to discuss the applicable. differences of the the Vzp dependence with the F10.7 and the EUV indexes. TYPE: POSTER TYPE: POSTER DATE: 2012-03-13 – 17:35 DATE: 2012-03-13 – 17:35

P5.14 DIFFERENCES BETWEEN THE P5.15 SYNOPSIS OF LOW FREQUENCY DEPENDENCES OF EQUATORIAL F ELECTROMAGNETIC WAVES DE- REGION EVENING VERTICAL DRIFT TECTED BY C/NOFS: IMPLICATIONS ON F10.7 AND EUV FLUXES OVER FOR EQUATORIAL IONOSPHERIC BRAZIL MODELING

78 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Fernando Simões and Robert Pfaff variations due to recombination, but close to the magnetic equator and near sunset, when NASA Goddard Space Flight Center, Green- the F layer is high enough for the recombination belt, MD, USA process to be considered negligible, the electromagnetic ExB becomes the most important The Communications/Navigation Outage component. This paper will present the tempo- Forecasting System (C/NOFS) satellite is ral variations of the vertical drift approximated equipped with a three-axis double probe electric with the above technique and also the verti- field detector that provides continuous DC and cal plasma velocity derived using a new tech- AC electric field measurements, and two opti- nique based on the numerical solution of the cal sensors for lightning detection. Among the continuity equation, both obtained for the qui- significant measurements thus far, C/NOFS etest days from the COPEX campaign (Octo- detected low frequency electromagnetic wave ber to December of 2002, high solar activity) signatures related to Ionospheric Alfven Res- near sunset hours. We will compare the vertical onator (IAR) and Schumann resonance phe- ExB drift simultaneously in two magnetically nomena. We present these findings in the con- conjugated stations and at a magnetic equator text of troposphere-ionosphere coupling mech- station, and analyze the differences and their anisms, namely lightning activity, electromag- possible causes in terms of meridional winds. netic wave propagation in the ionosphere, and tropospheric-space weather connections. We TYPE: POSTER discuss how these measurements can be com- DATE: 2012-03-13 – 17:35 bined with other techniques to improve empirical models of the ionosphere, in particular during the last solar minimum. Specifically, IAR P5.18 COORDINATE INVESTIGATION spectral signatures measured by C/NOFS con- OF THE F2 LAYER STRATIFICATION tribute to refine ion composition and the elec- AT LOW-LATITUDE IONSOPHERE: RE- tron density profile. SULTS FROM THE COSMIC AND GIRO

TYPE: POSTER Biqiang Zhao DATE: 2012-03-13 – 17:35 Institute of Geology and Geophysics, Chinese Academy of Sciences, China P5.17 VERTICAL EXB DRIFT DUR- ING PRE-REVERSAL PEAK HOURS Global observations of electron density pro- AT MAGNETICALLY CONJUGATE STA- file (EDP) from the COSMIC/FORMOSAT?3 TIONS IN BRAZIL (COPEX CAMPAIGN) satellites were used to investigate, for the first USING DIGISONDE DATA time, the additional stratification of the F2 Cláudia Vogel Ely1, Inez Staciarini Batista1, layer over the equatorial ionosphere on a global and Alexander José Carrasco2 scale, which is called F3 layer. The F3 layer in EDP was recognized through the altitude 1 Instituto Nacional de Pesquisas Espaciais - differential profile featured by two maxima ex- INPE, Sao Jose dos Campos, SP, Brazil isting from 220 km to the peak height of the 2 Universidad de Los Andes, Mérida, Venezuela electron density. There were 9,400 cases of F3 layer selected out of 448, 000 occultation The time variation of the F layer height at events at low and equatorial areas during the specific frequencies (dh(f)/dt) can be used to period of April 2006 - September 2011. Statis- estimate the vertical plasma velocity of the F tical results show that the highest occurrence layer. This apparent velocity has contributions of F3 layer appears at dip latitude 7 8°/-7 -8° from the electromagnetic ExB drift, from the for Northern/Southern Hemisphere and is more meridional neutral wind and from the height pronounced during summer months at 10:00

79 ISEA13 - 13th International Symposium on Equatorial Aeronomy

- 14:00 LT. The occurrence also has a clear solar activity periods in the last century. In the longitude dependence during boreal summer, present paper, an attempt has been made to with relatively higher occurrence at -80 -100°,- study the seasonal, diurnal and latitudinal vari- 20 20°, 80 120° and -160 -170° longitudes, that ation of electron density profiles obtained us- is possibly associated with the wavenumber-3 ing COSMIC radio occultation (RO) measure- diurnal tide (DE3). Meanwhile, the charac- ments over Indian low latitude region during teristic of the sunset F3 layer is first inves- the year 2008 when such deepest solar mini- tigated using a solar cycle of ionosonde data mum occurred. These observations are com- (1995–2010) from the magnetic equatorial sta- pared with previous low and high solar activity tion at Jicamarca, and compared with the fea- periods. The diurnal variation of electron den- tures derived from the GIRO stations at Sao sity suggests that enhanced electron densities Luis, Fortaleza, Kwajalein, Sanya, Fuke. Ev- are observed in the equinox season as compared idence shows that the local time distribution to that of winter and summer seasons. How- of the occurrence of the F3 layer can extend ever, there is a shift in the time and altitude at to the postsunset time (1800–2100 local time). which the peak of the electron density occurs The sunset F3 layer has a strong seasonal de- during equinox. While these observations fur- pendence occurring mainly during the summer- ther re-confirm that these results are quiet sim- time and with a preference at Jicamarca. Un- ilar to that of high solar activity period, how- like the daytime F3 layer, the occurrence of ever, the peak electron density obtained during the sunset F3 layer clearly increases with in- low solar activity is relatively low as compared creasing solar activity. These features of the to that of high solar activity period. The lati- dependence on the season, solar activity, and tudinal and seasonal variation of peak electron longitude are clearly related to the geomagnetic density (NmF2) indicates an enhanced EIA on control of the evening prereversal enhancement either-side of the equator during equinoxes as of the equatorial zonal electric field and merid- compared to the other seasons. Seasonal varia- ional winds modulated by the geomagnetic con- tion of EEJ strength during the same year also figuration. shows enhanced EEJ strength during equinoxes indicating that EEJ strength is indeed partly TYPE: POSTER controls the EIA development. Further, NmF2 DATE: 2012-03-13 – 17:35 over EIA are correlated very well with solar flux. In addition, the observed mean NmF2 and hmF2 obtained using COSMIC at different P5.19 SEASONAL AND DIURNAL BE- seasons are compared with SAMI2 model. The HAVIOR OF THE IONOSPHERIC F results suggest that while observed NmF2 are LAYER OVER INDIAN REGION DURING much higher than that of model, hmF2 obser- EXTREMELY LOW SOLAR ACTIVITY vations show that COSMIC observed values are CONDITIONS AS OBSERVED BY COS- lower than that of model results. While some MIC discrepancies exist between model and COS- Samireddipalle Sripathi MIC which needs further investigation, overall, the model seems to agree with COSMIC obser- Indian Institute of Geomagnetism, Navi Mum- vations for the Indian longitudes. bai, India TYPE: POSTER Solar activity during the year 2007-2009 DATE: 2012-03-13 – 17:35 was the deepest and longest among other low

80 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 6

IONOSPHERIC STORMS AND SPACE WEATHER EFFECTS AT LOW AND MID LATITUDES

Response of the equatorial-, low-, and mid-latitude ionosphere to geomagnetic storms is extremely complex and calls for focused attention addressing the consequences of various space weather effects. During geomagnetic storms, time varying magnetosphere-ionosphere-thermosphere interactions at high latitudes cause a host of disturbances, such as, large scale traveling atmospheric/ionospheric disturbances, under/overshielding and disturbance dynamo electric fields, and dramatic variations in the total electron content. All these show global scale signatures, and do have a great influence on ionosphere/thermosphere at mid-, low-, and equatorial latitudes, which could also result in the generation of plasma irregularities. Human activities today depend so much on the high technology applications in the near earth space, such as satellite operations, aviations, radio wave communications, and Global Navigation Satellite System (GNSS) positioning, and the accuracies in these measurements are ad- versely affected by the gradients in electron contents and plasma irregularities. Thus, experimental, theoretical, and modeling efforts are all extremely essential for improving our understanding of the ionospheric/thermospheric disturbances at all latitudes during geomagnetic storms and substorms. Recent progress in space-based (TIMED, CHAMP, COSMIC, C/NOFS), and ground-based (Radars, GNSS receivers, optical sensors, magnetometer chains) observations has allowed us to diagnose space weather effects in geospace. Furthermore, advancement in theory and modeling efforts help us elucidate the underlying physics in the observations. Specific topics to be discussed in this session are: (1) Storm time variations in ionospheric plasma and electrodynamics, (2) Prompt penetration and disturbance dynamo contributions in the storm time electric field, (3) Ionospheric scintillations due to space weather during both quiet and disturbed conditions, at low and mid-latitudes. This session, therefore, welcomes presentations of all aspects of the response of the equatorial-, low-, and mid-latitude ionosphere to the space weather effects.

Keywords:

• Experiment, theory, modeling eﬀorts

• Magnetic storms and substorms

• Disturbance dynamo and promptly penetrated electric ﬁelds during the storm time condition

81 ISEA13 - 13th International Symposium on Equatorial Aeronomy

• Ionospheric plasma variations and electrodynamics during storms

• Space weather eﬀects during quiet times.

• Ionospheric Scintillation during the quiet and disturbed conditions

Conveners: H. Takahashi, D. Pallamraju, and N. Maruyama

82 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - THREE-DIMENSIONAL the dawn sector first discovered from observa- MODELING OF EQUATORIAL BUB- tions made by the Communications/Navigation BLES Outage Forecast System (C/NOFS) equatorial satellite (O. de la Beaujardiere, private com- 1 2 3 Joseph Huba , G. Joyce , and J. Krall munication, 2010). Related discoveries suggest that the majority of solar minimum equa- 1 Plasma Physics Division, Naval Research Lab- torial plasma bubbles occur post-midnight, in oratory, USA contrast to the typical post-sunset formation 2 Icarus Research, Inc., Bethesda, MD, USA documented during previous solar cycles. This 3 Naval Research Laboratory, USA paper addresses the climatology and physics The NRL three-dimensional ionospheric of ground-based scintillation observations dur- simulation code SAMI3 is used to model the on- ing the same extended solar minimum period. set and evolution of plasma bubbles associated The results show that scintillation occurrence with equatorial spread F (ESF). SAMI3 is a is largely consistent with observations from all comprehensive ionosphere model that has been phases of the solar cycles and little to no en- modified to self-consistently solve for the global hancement in post-midnight F-region irregulari- neutral wind driven dynamo electric field as well ties occurs. This suggests that the physical pro- as the gravity driven electric field associated cesses leading to the formation of ionospheric with plasma bubbles. The latter is achieved irregularities during the extended solar mini- with a high resolution longitudinal grid in the mum period are in fact the same processes that pre- to post-sunset sector (i.e., 1630 MLT - cause irregularities throughout the solar cycle. 2230 MLT). Results from the new simulation The amplitudes and rates at which these pro- model are presented. It is shown that ESF can cesses occur may, however, vary significantly be triggered by pre-sunset ionospheric density with solar activity. The disparity in the space- perturbations, and that an existing ESF bubble and ground-based results may be explained by can trigger a new bubble. We will also dis- considering two factors. First, the altitude bias cuss the generation of equatorial bubbles dur- of the in situ satellite observations results in a ing disturbed times when storm-time penetra- failure to detect irregularities below the satel- tion or dynamo disturbance electric fields affect lite altitude. Direct radar observations of bub- the low-latitude ionosphere. ble formation indicate that bubble ascent rates and peak heights decrease during solar mini- TYPE: ORAL mum. Many bubbles simply do not reach typi- DATE: 2012-03-14 – 08:00 cal satellite altitudes above 500 km during periods of low solar flux; those that eventually do arrive later in local time due to lower vertical EQUATORIAL SCINTILLATION ACTIV- drifts. The altitude bias of space-based obser- ITY DURING EXTENDED SOLAR MINI- vations then results in a distribution of plasma MUM bubbles that is both reduced in number and Keith Groves shifted to later local time. Second, scintillation observations are sensitive to the absolute differ- Boston College, MA, USA ences in density along the radio wave raypath, not the relative variations. If the background As space weather scientists and operational electron density becomes sufficiently low the users anxiously await an increase in solar activ- structured plasma simply cannot cause scin- ity, satellite observations have led several inves- tillations. Thus, scintillations may not occur tigators to report new ionospheric features pur- during solar minimum in the low density post- portedly unique to the low-latitude ionosphere midnight time period even though irregularities during the recent prolonged solar minimum pe- are present. A consideration of these factors riod. The most prominent of these is the occur- leads to more consistent agreement between rence of large-scale deep density depletions in

83 ISEA13 - 13th International Symposium on Equatorial Aeronomy space- and ground-based observations during latitude thermospheric zonal and meridional/ solar minimum and helps to identify what iono- trans-equatorial winds are the main agencies spheric characteristics are unique to the ex- that control the storm time ESF development tended solar minimum of 2006-2009. process, which is dependent also on season and longitudes. Our current understanding of the TYPE: ORAL above factors and some outstanding questions DATE: 2012-03-14 – 08:20 of the ESF variability arising therefrom, as revealed by recent results from observational as well as modeling studies will be covered in this INVITED - STORM TIME VARIABILITY talk. IN EQUATORIAL SPREAD F/PLASMA BUBBLE IRREGULARITY DEVELOP- TYPE: ORAL MENT DATE: 2012-03-14 – 08:35

Mangalathayil Ali Abdu, Inez Staciarini Batista, Jose Sobral, Angela M. Santos, and SPACE WEATHER AND GEOSPACE EF- Paulo Nogueira FECTS OF STORM-TIME THERMAL PLASMA REDISTRIBUTION Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP, Brazil John Foster

The equatorial spread F/plasma bubble ir- MIT Haystack Observatory, Massachusetts In- regularity development is known to be constitute of Technology, MA, USA trolled by sunset electrodynamics processes in which the rapid changes from the day-to- Storm-time thermal plasma redistribution night transition of the background ionosphere- provides an excellent example of the cross- thermosphere system play major roles. The discipline, system-level Geospace problems leading factors that determine the ESF growth which are a focus of the recent CEDAR Strate- process are: the enhanced prereversal vertical gic Plan. Many aspects of this Geospace pro- drift (PRE) associated with the plasma vor- cess have been observed from the ground and tex flow, the thermospheric meridional/trans- space during the major geomagnetic storms of equatorial winds, and gravity wave perturba- the past solar cycle. When viewed in the con- tions in plasma density and polarization elec- text of the geospace storm taken as a whole, tric fields as seed perturbations for the R-T plasma redistribution is seen as a multi-step instability growth. During magnetic storms system-wide processes involving the equatorial, the drastic change that occur in these pa- low, mid, auroral, and polar-latitude regions. rameters, especially in the first two, together Penetration electric fields uplift the low-latitude with the modification of the large scale spa- dayside ionosphere and enhance the equato- tial distribution in ionospheric conductivity, can rial ionization anomaly peaks, while polariza- cause significant modifications to the develop- tion electric field effects at the dusk terminator ment and dynamics of the plasma bubble ir- redistribute the low-latitude TEC in both lon- regularities. Enhanced development of the ir- gitude and latitude. Magnetic field geometry regularities followed by their anomalous drifts, creates a preferred longitude for the enhance- and suppression or disruption of the irregular- ment of low and mid-latitude TEC in the Amer- ity generation has been reported for the dif- ican sector at the sunset. These TEC enhance- ferent storm phases. Prompt penetration elec- ments form a localized source for the intense tric fields of under-shielding and over-shielding storm enhanced density (SED) erosion plumes types, the disturbance dynamo electric field which originate over the Americas during major originating from the storm energy input and au- storms. High-TEC SED plumes produce sig- roral heating, as well as the disturbances in low nificant space weather effects associated with

84 ISEA13 - 13th International Symposium on Equatorial Aeronomy the steep TEC gradients which develop along were characterized by the well-pronounced pos- their edges, particularly at their poleward bor- itive effect observed in the ionosphere at the der where the SED overlaps the SAPS flow dayside. In the given study we used data of channel. Magnetospheric and M-I coupling GPS TEC estimates retrieved from observa- processes lead to the development of the sub- tions of European mid-latitudes GPS receivers, auroral polarization stream (SAPS), the ero- ionosonde measurements from DIAS network sion of the plasmasphere boundary layer, and and FORMOSAT-3/COSMIC radio occultation the transport of SED material to the noontime (RO) measurements. The short-duration posi- cusp. These greatly-enhanced fluxes of lower- tive effect was revealed distinctly in GPS TEC latitude heavy (O+) ions traverse the cusp and and ionosondes’ measurements. For the case enter the polar cap forming the polar tongue of of October 11, 2008 the strong TEC increase ionization and providing a rich source of iono- over European region has rather short dura- spheric heavy ions for the magnetospheric injec- tion (11-15 UT) and its amplitude reached tion and acceleration mechanisms which oper- the maximum value of 9 TECU (100% rela- ate in these regions. Further geospace weather tive to the quiet conditions). This enhance- effects occur as the newly-injected ionospheric ment was clearly observed in the foF2 variations heavy ions alter reconnection, ring current, and over ionospheric stations Juliusruh, Pruhonice WPI processes. These affect storm develop- and Rome. The clear positive effect was ob- ment, changes in the radiation belts, and ener- served for the second event too. Special atten- getic particle precipitation. tion was paid to estimation of ionospheric electron content (IEC) during storms. The electron TYPE: ORAL density profiles derived from the COSMIC RO DATE: 2012-03-14 – 08:55 measurements were also involved into analysis. These profiles were integrated up to the height of NmF2 and top in order to obtain COSMIC- RESPONSE OF THE MID-LATITUDE derived IECb (bottom side) and IECt (topside) IONOSPHERE TO GEOMAGNETIC estimates. Ionosonde-derived Ne profiles were STORM ON OCTOBER 11, 2008 AND also integrated. The vertical GPS TEC esti- OCTOBER 11, 2010 mates was split into two contributions, one part due to the bottomside ionosphere and other Irina Zakharenkova, Iurii Cherniak, and Irk part due to the topside ionosphere. The topside Shagimuratov part of TEC contains IECt and PEC (plasmaspheric electron content). So, the joint compar- West Department of IZMIRAN, Kaliningrad, ison of GPS TEC, COSMIC IEC and ionosonde Russia IEC values was carried out in order to estimate redistribution of electron content for quiet and The ionosphere behavior over European disturbed conditions. mid-latitudes during moderate geomagnetic disturbances which occurred on October 11, TYPE: ORAL 2008 and October 11, 2010 was analyzed. DATE: 2012-03-14 – 09:10 These events are interesting as they occurred during a period of very low solar activity; the first one took place at the unusual extended IONOSPHERIC SUPERSTORM DRIVERS: solar minimum, the second one – at the begin- THE ROLE OF THE ATLANTIC SEC- ning of new 24th solar cycle. Local time of the TOR POLARIZATION TERMINATOR ionospheric storms’ beginning was practically the same. Thus, the objective of this paper Philip Erickson and John Foster was to analyze similarities and differences of the ionosphere response to these events. Relatively MIT Haystack Observatory, Massachusetts In- weak but isolated geomagnetic disturbances stitute of Technology, MA, USA

85 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Large enhancements of ionospheric to- DATE: 2012-03-14 – 09:25 tal electron content (TEC) in the coupled geospace system often occur during daytime geomagnetically disturbed intervals. Several SPACE WEATHER PROGRAM IN potential mechanisms can contribute to these BRAZIL enhancements by causing increased production, Hisao Takahashi, Joaquim E R Costa , Alisson reduced recombination, and/or redistribution Dal Lago, Clezio Marcos De Nardin, Eurico De of solar produced plasma from other spatial Paula, Jonas Rodrigues De Souza, Antonio L. regions. These drivers can include uplift due Padilha , Nilson Sant Anna , Rubens C. Gatto, to penetration electric fields, equatorial neu- and Oswaldo D. Miranda tral winds, traveling atmospheric disturbances, strong poleward ionization drifts, changes in Instituto Nacional de Pesquisas Espaciais - neutral chemistry and/or a greatly expanded INPE, Sao Jose dos Campos, SP, Brazil auroral convection field. However, in the dusk sector, additional processes may be involved in Brazilian Space Weather program (EM- creating spatially and temporally localized TEC BRACE) started at INPE in 2008. It is aimed to increases. These effects can provide a signifi- establish “Space Weather Information and Pre- cant dusk plasma buildup in the Caribbean sec- diction Center” upto 2012/2013. The center tor and simultaneous enhancements in magnet- has objectives to monitor the solar activity and ically conjugate regions, through poleward and its impact on the earth"s space environment, westward motion of low latitude plasma on the and to predict the influence on the space-based night side towards the vicinity of the dusk ter- and ground-based technological systems. Our minator. specific concerns are to monitor peculiar physical processes in the equatorial ionosphere, such In this presentation, we will emphasize as equatorial electrojet, the ionization anomaly ionospheric response mechanisms involving a and the plasma bubbles. These processes af- combination of the stormtime penetration elec- fect radio wave propagation and GNSS ap- tric field, reduced magnetic field strength in plications. The South Atlantic geomagnetic the South Atlantic magnetic anomaly, and the anomaly (SAGA) is also a great concern for geographic distortion of the magnetic field in satellite operations. Groundbased monitoring the Atlantic sector. The resulting effects lead system consists on solar radio telescopes, con- to characteristics of electric fields at the sun- jugate point ionospheric sounders, GNSS re- set terminator which can account for many ob- ceivers, magnetometer arrays, optical imagers, served plasma intensification and redistribution radio frequency radars, as well as ground in- features in lower mid-latitudes in the American duced current sensors. Recent progress in these sector. In particular, the combination of effects monitoring system and related space weather characteristic of the unique magnetic field ge- information will be presented. ometry in that sector lead to strong intensification of storm enhanced density plumes over TYPE: ORAL the Americas, which are subsequently fed into DATE: 2012-03-14 – 09:40 the sub-auroral polarization stream and carried toward high latitudes. These qualities mark INVITED - EFFECTS OF SPACE the Atlantic sector as a preferred longitude or WEATHER OVER LOW LATITUDES: Universal Time sector for extreme geospace RECENT RESULTS USING OPTICAL responses to geomagnetic disturbances. For AND OTHER TECHNIQUES events when these mechanisms are prominent, the effects are predicted to be strongest for Dibyendu Chakrabarty northern hemisphere summer conditions. Physical Research Laboratory, Ahmedabad, In- TYPE: ORAL dia

86 ISEA13 - 13th International Symposium on Equatorial Aeronomy

It is known that the ionosphere over low- DATE: 2012-03-14 – 10:25 equatorial latitudes is subjected to radiative perturbations during solar flares. On the other hand, the electric field disturbances can arise BOUNDARY CONDITIONS ON MAG- due to the prompt penetration/overshielding NETOSPHERIC CONVECTION AT THE effects of interplanetary electric field (IEF), dis- DIP EQUATOR AND PENETRATING turbance dynamo, storm sudden commence- ELECTRIC FIELDS ment (SSC) and substorms. The time scales of these processes can range from a few min- Vytenis M. Vasyliunas utes to several hours. Simultaneous presence Max Planck Institute for Solar System Re- of these effects can be a hindrance to gauge search, Lindau, Germany the impact of an individual process on the low latitude ionosphere. Therefore, observa- The flow pattern of magnetospheric con- tions by multiple techniques are needed to de- vection is frequently described by specifying the lineate these effects. The talk will address a electrostatic potential at the top of the iono- few of such observations. In recent times, op- sphere as function of latitude and local time. tical observations in conjunction with other in- From magnetosphere/ionosphere coupling the- dependent measurements are used to decipher ory, this potential function is determined as the the effects of space weather over low latitudes. solution of a second-order partial differential It is shown that narrow-spectral band, narrow equation of elliptic type, subject to suitable field-of-view airglow photometry of the 630.0 boundary conditions. Most attention is usu- nm nocturnal airglow emission can detect the ally directed to the boundary condition at high prompt penetration of interplanetary electric latitudes, representing the direct effects of in- field (IEF) into low latitude ionosphere with teraction with the solar wind, but the boundary high temporal resolution. A scanning mirror condition at the equator must also be specified; arrangement on top of the photometer can pro- conventionally it is taken as zero meridional vide observations at different spatial locations. current, applied not at the equator itself, how- Thus, the variations in 630.0 nm airglow in- ever, but at latitude near 20 degrees (to avoid tensity observed in two different directions are singularities of zero inclination angle). Alter- used to investigate the triggering of Equato- natively, it could be taken as zero meridional rial Spread-F (ESF) under the influence of IEF. flow. Mathematically, the two choices corre- Using this instrument and monitoring 630.0 nm spond to Neumann and Dirichlet conditions, and 777.4 nm airglow emissions at two different respectively; physically, they represent different view angles (zenith and 45o East), optical sig- assumptions about the local interface between nature of shear in the zonal plasma flow along the ionosphere and the magnetosphere, with with a tilted plasma plume structure associ- significant implications for the physical mecha- ated with ESF during a space weather event nism of establishing prompt penetration electric is identified. It is also shown that 630.0 nm fields at low latitudes. airglow emission over low latitudes can get affected by the substorm-related transient elec- TYPE: ORAL tric field perturbations and it is possible to DATE: 2012-03-14 – 10:45 delineate the substorm-related signatures from the IEF-related perturbations. In addition to the above results, the delineation of the effects IONOSPHERIC EFFECTS OF SEVERAL of lesser rank X-class solar flares from the tran- SUPER STORMS AT LOWER LATI- sient effects of the magnetic storm/susbtorm TUDES IN SOUTH AMERICAN SECTOR on the equatorial ionosphere will also be dis- 1 1 cussed Vladimir Klimenko , Maxim Klimenko , Yo- geshwar Sahai2, Alessandro De Abreu2, Paulo TYPE: ORAL Fagundes3, and Rodolfo De Jesus2

87 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 West Department of Pushkov Institute of these studies are presented and discussed. It Terrestrial Magnetism, Ionosphere and Radio is shown that during geomagnetic storms, the Wave Propagation RAS, Kaliningrad, Russia non-uniform in height zonal electric ﬁeld at ge- 2 Department of Physics and Astronomy, Uni- omagnetic equator forms the additional peaks versidade do Vale do Paraiba, Sao Jose dos in the upper part of the electron density proﬁle. Campos, Brazil 3 Universidade do Vale do Paraíba, Sao Jose TYPE: ORAL dos Campos, Brazil DATE: 2012-03-14 – 11:00

This study presents the Global Self- consistent Model of the Thermosphere, Iono- OBSERVATION OF UNEXPECTED FEA- sphere and Protonosphere (GSM TIP) numeri- TURES IN THE EQUATORIAL ELEC- cal simulations of the several super storms ef- TRODYNAMICS DURING A DISTUR- fects in the low-latitude ionosphere. It was BANCE DYNAMO EPISODE AND THE considered the super storms with |Dst| > 250 NEUTRAL WIND SIGNATURES THAT nT, four periods with super storm events have THEY IMPLY been analyzed: 05–08 April 2000, 27–31 Octo- Jean-Pierre St-Maurice1, Raj Kumar ber 2003, 19–23 November 2003, and 06–11 Choudhary2, K. M. Ambili2, and R. Sridha- November 2004. Recent modifications to ran 3 the GSM TIP model include adding empirical model of high-energy electron precipitation 1 University of Saskatchewan, Canada and introducing a high-resolution (1-min) cal- 2 Space Physics Laboratory, Trivandrum, India culation of region 2 field aligned currents (R2 3 Physical Research Laboratory, Ahmedabad, FAC) and a cross-polar cap potential (CPCP). India We also have included the 30 min time delay of R2 FAC variations with respect to the A disturbance dynamo was observed in the variations of CPCP. These modifications re- magnetic equatorial region of the Asian sub- sulted in better representation of such effects as continent on May 31, 2005, one day after an penetration of magnetospheric convection elec- intense magnetic storm of relatively short du- tric field to lower latitudes and the overshield- ration. At first sight, there was nothing un- ing. To compare the calculation results we usual about the May 31 event, with ground- used the experimental data of Total Electron based magnetograms revealing the expected Content (TEC) from GPS receivers in South very strong reduction in the normal mid-day America: Belem (BELE; 1.5°S,48.5°W), Imper- electrojet and basically a complete disappear- atriz (IMPZ; 5.5°S, 47.5°W), Brasilia (BRAZ; ance of the Equatorial Ionization Anomaly, as 15.9°S, 47.9°W), Presidente Prudente (UEPP; revealed by observations of Total Electron Con- 22.3°S, 51.4°W), Porto Alegre (POAL; 30.1°S, tent (TEC) data. However, a careful study 51.1°W), La Plata (LPGS; 34.9°S, 57.9°W), of ionosonde data at the magnetic equator and Bahia Blanca (VBCA; 38.7°S, 62.3°W). We strongly suggested that, contrary to conven- gave a particular attention to the main iono- tional thinking, the F region zonal electric field spheric drivers, such as electric field dynamo had remained eastward throughout most of the and magnetospheric origin, meridional compo- day (with possibly a very brief reversal before nent of thermospheric wind and neutral at- the noon hour), this in spite of indications for mosphere composition variations. The model reversal in the magnetic perturbations observed results show both similarities and differences from the ground. The most remarkable obser- from the observational results. Large positive vation on that day was not that, however, but and negative variations in the TEC during the rather a large mid afternoon amplification of main and recovery phases compared to quiet the eastward zonal field that was followed by day variation were observed in several super a westward turning after 1600 IST. Interest- storm events studied. Salient features from ingly, this oscillation triggered a depletion in the

88 ISEA13 - 13th International Symposium on Equatorial Aeronomy equatorial TEC, but without an accompanying ing/noon time. The morning eastward pen- modulation of the TEC in the anomaly crest re- etration electric field over the equator man- gion. Instead, the equatorial TEC returned to ifested as strong ExB vertical drift and sub- its pre-depletion value when the plasma came sequent formation of high altitude F3 layer through the downward phase of its oscillation. inferred from the ionogram traces. Interest- These unexpected signatures could all be ex- ingly, the noon time westward penetration re- plained if the disturbed dynamo neutral wind sulted in unexpected changes over the equa- properties obeyed two constraints, namely, (1) tor. It was characterized by strong depletion the neutral wind circulation cell due to Joule of thermosphere OI 630.0 nm dayglow. The heating did not reach the magnetic equator dayglow observations were carried out using but came close enough to it to essentially kill a unique Multiwavelength dayglow photometer the equatorial fountain effect while maintain- (MWDPM). Further analysis of magnetometer ing an eastward zonal field; (2) a weakening observations over Trivandrum and an offequa- of the high latitude-driven Hadley cell circu- torial station, Alibag (18.60 N, 72.9 0 E, dip lation in the mid-afternoon hours could have 12.8 0 N) revealed that there is a drastic de- easily produced the observed equatorial F re- crease in cowling conductivity during this time. gion zonal electric field oscillation, creating a It is verified that this is due to the strong neu- situation that was highly reminiscent of the tral heating ( 30 K) at lower E region ( 90 equatorial "Pre-Reversal-Enhancement" signa- km), the proof being high mesopause temper- ture normally observed near the terminator in- ature, as estimated using MWDPM measure- stead of the mid-afternoon. ments. The adiabatic expansion of the MLTI region due to this strong heating in the lower TYPE: ORAL E region resulted in the significant intrusion DATE: 2012-03-14 – 11:15 of more molecular N2 into higher altitudes. This significantly reduced the cowling conductivity at EEJ altitudes due to the increased ion- ON THE VARIABILITY OF THE THER- neutral collisions and subsequently quenched MOSPHERIC 630.0NM DAYGLOW OW- the O(1D) atoms at the dayglow emitting alti- ING TO THE SIMULTANEOUS FORC- tudes. The importance of the present study lies ING DUE TO STRONG NEUTRAL in showing the emphatic changes in the equato- HEATING IN THE MESOPAUSE AND rial ionosphere thermosphere system including A NOON TIME PENETRATION OF IN- the mesopause regions in conjunction with the TERPLANETARY ELECTRIC FIELD prompt penetration electric fields.

S. G. Sumod and T. K. Pant TYPE: ORAL DATE: 2012-03-14 – 11:30 Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum, India INSTALLATION OF ELECTRIC FIELD The paper for the ‘first time’ presents MONITORS AT PUNTA LOBOS AND the evidence for the strong neutral heating ICA, PERU in the Mesosphere Lower Thermosphere Iono- sphere (MLTI) region over a magnetic dip equa- Edith Macotela1, Jean-Pierre Raulin2, Wal- torial station, Trivandrum in India (8.50 N, ter Guevara1, Cristian Ferradas1, and Carlos 770 E, 0.50 N) concomitant with the pene- Euribe3 tration of noon time westward Interplanetary electric field. The day on April 09, 2006 1 Comisión Nacional de Investigación y Desar- was very special, as it is characterized by the rollo Aeroespacial, Lima, Perú eastward/westward penetration of interplane- 2 Centro de Radio Astronomía e As- tary electric field over equator during morn- trofísica Mackenzie, Universidade Presbiteriana

89 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Mackenzie, Brazil observed by ground magnetometers and radar. 3 Universidad Nacional San Luis Gonzaga de We show that the magnetometer estimated Ica, Perú equatorial ExB drift oscillate with the same frequency as ULF Pc5 waves, creating significant We present the installation and calibration ionospheric density fluctuations. For indepen- of two electric field monitors (EFM-100) at dent confirmation of the vertical drift velocity Punta Lobos and Ica stations. The main objec- fluctuation, we used JULIA 150 km radar drift tives of the electric field monitoring operation velocities and found similar fluctuation with the are the study of diurnal and long term varia- period of 8-10 minutes. We also show iono- tions of the atmospheric electric field due to spheric density fluctuations during the period terrestrial (earthquakes) and solar phenomena. when we observed ULF wave activities. All The stations started their operations in Novem- these demonstrate that the Pc5 wave can pen- ber and December respectively. etrate to the equatorial ionosphere and modulate the equatorial electrodynamics. Finally, TYPE: ORAL in order to detect the ULF activities both on DATE: 2012-03-14 – 12:00 the ground and in space, we use groundbased magnetometer data from African Meridian B- field Education and Research (AMBER) and OBSERVATIONS OF ULF WAVE RE- the South American Meridional B-field Array LATED VERTICAL DRIFT VELOCITY (SAMBA). From space, we use magnetic field AND DENSITY FLUCTUATIONS observations from the GOES 12 and the Com- munication/Navigation Outage and Forecast 1 2 Endawoke Yizengaw , Eftyhia Zesta , Mark System (C/NOFS) satellites. Using the WIND 3 4 5 Moldwin , Baylie Damtie , Fatma Anad , and spacecraft as the upstream solar wind moni- 6 Robert Pfaff tor, we present direct evidence that solar wind number density and ram pressure fluctuations 1 Boston College, MA, USA observed far upstream from the terrestrial mag- 2 Air Force Research Laboratory, USA netosphere are the main drivers of ULF wave 3 Department of Atmospheric, Oceanic and activity inside the magnetosphere. Finally, we Space Sciences, University of Michigan, MI, show that the ULF waves in the same frequency USA range are observed in the magnetosphere by the 4 Bahir dar University, Ethiopia geosynchronous GOES spacecraft, in the iono- 5 Centre de Recherche en Astronomie Astro- sphere by the equatorial C/NOFS satellite, and physique et G?ophysique, Algerie on the ground by ground-based magnetome- 6 NASA Goddard Space Flight Center, Green- ters, indicating that the magnetospheric origin belt, MD, USA ULF wave can penetrate to the ground equatorial region and modulate the equatorial elec- Global magnetospheric Ultra Low Fre- trodynamics quency (ULF) pulsations with frequencies in the Pc 4-5 range (f = 1.0 – 8 mHz) have TYPE: ORAL been observed for decades in space and on DATE: 2012-03-14 – 12:15 Earth. ULF pulsations contribute to magnetospheric particle transport and diffusion and play an important role in magnetospheric dy- P6.05 FEATURES OF THE IONO- namics. However, only a few studies have been SPHERIC STORMS’ OCCURENCE AT performed on ionospheric observations of ULF LOW SOLAR ACTIVITY PERIOD wave-related perturbations in the vicinity of the Iurii Cherniak and Irina Zakharenkova equatorial region. In this paper we report on Pc5 wave related electric field and thus verti- West Department of IZMIRAN, Kaliningrad, cal drift velocity oscillations at the equator as Russia

90 ISEA13 - 13th International Symposium on Equatorial Aeronomy

During the years of extended solar minimum and at the beginning of the new 24th solar cycle several geomagnetic storms took place. In P6.08 RESPONSE OF THERMAL this study we analyzed the geomagnetic distur- AND SUPRA-THERMAL IONOSPHERIC bances occurred on October 2008, July 2009, PLASMA TO ENERGY INPUT FROM May 2010 and March, August and Septem- MAGNETOSPHERE AND ATMO- ber 2011, which caused the most appreciable SPHERE DURING MAGNETOSPHERIC ionospheric response. The ionospheric changes AND THUNDER-STORMS: DEMETER during these events were analyzed by using OBSERVATIONS the multi-instrumental diagnostic facilities data Elena Seran and Michel Godefroy such as “Parus” ionosonde in Kaliningard observatory, the ionospheric measurements data CNRS-LATMOS, France provided by European, Japanese and Australian ionosonde networks. The global ionospheric We present and discuss few examples of maps of TEC (GIMs TEC) provided by In- plasma observations made in ionosphere at 700 ternational GNSS Service were used in or- km by CNES micro-satellite Demeter during der to estimate global storm effects. For de- magnetospheric and thunder-storms. The con- tailed analysis of the height ionospheric struc- jugated observations of onboard ion retarding ture changes we combined ionosonde-derived & drift analysers and electric field antennas data with the electron density profiles retrieved (both developed by the LATMOS team) to- from FORMOSAT-3 / COSMIC radio occulta- gether with remote optical imagers and VLF tion measurements. The peak electron density antennas allow to analyse the perturbations (foF2) variations, shape of the electron den- of the plasma parameters (ions composition, sity profiles and global GPS TEC distribution drift and field-aligned motion, temperature and were analyzed. The geomagnetic storms with density of thermal and suprathermal popula- similar magnitude lead to the different iono- tion) with respect to the variation of the field- spheric response (positive and negative) over aligned currents, the electron and proton pre- European, Japan and Australian regions. The cipitation, the power and localisation of electric temporal and quantitative characteristics of the discharges. ionosphere modification during selected geomagnetic storms were revealed. It was car- TYPE: POSTER ried out the comparison of measurement results DATE: 2012-03-15 – 17:30 with IRI-2007 model, that have the storm-time option. It was obtained the qualitative agree- P6.09 THE AUGUST 2011 URSI WORLD ment between the ionosonde-derived foF2 val- DAY CAMPAIGN: INITIAL RESULTS ues and model calculations for cases of negative ionospheric storms. The best agreement Thomas Immel and Guiping Liu between model and observations results cor- responds to the Northern Hemisphere midlat- University of California Berkeley, CA, USA itude stations. We acknowledge the European Digital Upper Atmosphere Server (DIAS), Aus- A coordinated low-latitude atmospheric- tralian IPS Radio and Space service and the ionospheric URSI World Day campaign was or- National Institute of Information and Commu- ganized for 1st-10th August 2011. This cam- nications Technology (NICT) in Japan for pro- paign brought together observations from a viding ionosonde data. We are also grateful wide-range of facilities, including the incoher- to International GNSS Service (IGS) for GIMs ent scatter radars (ISR) at Jicamarca, Arecibo, IONEX Data. Millstone Hill and Kharkov, low-latitude meteor and medium frequency radars, ground-based TYPE: POSTER Fabry-Perot interferometers and the C/NOFS DATE: 2012-03-15 – 17:30 and COSMIC satellites. All four ISRs were run

91 ISEA13 - 13th International Symposium on Equatorial Aeronomy in complementary modes to identify the behav- P6.12 A COMBINED OPTICAL AND ior of the atmosphere and ionosphere on hourly- RADAR APPROACH FOR DERIVING to-daily time-scales. This campaign also coin- PARTICLE FLUXES IN THE DAY- cided with some of the first scientific data to be TIME DURING GEOMAGNETIC DIS- taken by the CINDI wind instrument onboard TURBANCES C/NOFS. Here we present some of the initial results of the atmospheric and ionospheric be- Duggirala Pallamraju havior and coupling during this unique obser- Physical Research Laboratory, Ahmedabad, In- vational interval. Particular focus is placed on dia the response of the low-latitude system to the magnetic storm that occurred on August 6th Particle energies and fluxes have predom- when Dst reached below -100 nT. inantly been measured from instruments onboard satellites. A new approach is presented POSTER TYPE: in this study wherein energy estimation is done 2012-03-15 – 17:30 DATE: by remote method of using optical emissions as sensors in the sky. Knowing the production mechanism of an emission and the energy P6.11 ALGORITHM FOR SOLAR FLARE required to excite such an emission, informa- DETECTABILITY USING VLF WAVES tion on the incident particle energy can be in- FROM SAVNET STATION -PLO, PERU ferred. Traditionally, ratios of emissions with known excitation energies were used to infer Riano Escate1, Javier Rengifo1, Walter the particle energies. In one study, we used Guevara1, and Jean-Pierre Raulin2 daytime ground?based oxygen redline (OI 630.0 nm) emission measurements, along with the 1 Comisión Nacional de Investigación y Desar- ionospheric electron density, and electron tem- rollo Aeroespacial, Lima, Perú perature profiles measured from the incoherent 2 Centro de Radio Astronomía e As- scatter radar, and a physics?based modelling trofísica Mackenzie, Universidade Presbiteriana approach to derive the energy and flux of par- Mackenzie, Brazil ticles incident over Boston during the storm of 30 October 2003. Such approach has also been VLF waves are used to investigate the be- extended for investigations of particle energies havior of the lower ionosphere in response to at high-latitudes and a progress on such efforts the ionizing radiation which principal source will be presented. Such an approach not only is the Sun. We present the proposal for a offers another method to estimate the incident method to perform statistic of SPA (Sudden particle energies and fluxes but also enhances Phase Anomaly) detected in the radio wave sig- our understanding on the channels of energy nal, and caused by solar flares, using digital deposition in the upper atmospheric region, es- records of the Punta Lobos SAVNET station pecially during magnetic disturbances. (CONIDA). The method proposes to develop a software to determine the sudden deflection of TYPE: POSTER the reconstructed curve from the VLF phase, DATE: 2012-03-15 – 17:30 during a solar flare event. For this propose, the digital data is operated in a matrix form, providing as a result the following parameters: P6.13 IONOSPHERIC BEHAVIOUR linear regression slopes on different timescales, OVER CYPRUS DRIVEN BY MODER- slope time variability, and SPA start time. ATE GEOMAGNETIC STORMS IN THE RISING PHASE OF THE CURRENT SO- TYPE: POSTER LAR CYCLE DATE: 2012-03-15 – 17:30 Haris Haralambous

92 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Frederick University, Cyprus changes if any on threshold height and its implications for ESF are brought out. Ionosonde In the course of the current year (2011) data, of Trivandrum (8.5° N, 76.5° E, dip = during the rising phase of solar cycle 24, three 0.5° N) and SHAR (13.7° N, 80.2° E, dip 5.5° geomagnetic storms of moderate intensity oc- N) in the Indian longitude sector, during winter curred due to coronal mass ejection and solar and equinox seasons of 2002 (solar maximum) wind stream impacting Earth’s magnetic field. and 2005 (low solar activity) have been used These storms occurred on March, May and Au- for the study. The study revealed that for both gust. In this paper, we present and discuss the the solar epochs, the threshold height is higher ionospheric response during these storms using for magnetically disturbed periods compared to TEC (Total electron content) and ionosonde quiet periods. This means that the neutral dy- data over Cyprus. Variation of TEC and foF2 namical control over ESF occurrence becomes and hmF2 ionospheric characteristics is studied more important during disturbed periods than in correlation with geomagnetic indices to re- during quiet period. It is also revealed that sim- veal temporal and spatial patterns during these ilar to the behaviour during magnetically quiet events. period, the threshold height increases with solar activity during disturbed period. It seems that TYPE: POSTER the temperature related effects on scale height DATE: 2012-03-15 – 17:30 which is the suggested causative mechanism for increased threshold height during high solar activity of magnetically quiet period is equally ef- P6.14 ON THE SEASONAL AND SOLAR fective in producing similar effects during dis- ACTIVITY VARIABILITY OF THRESH- turbed periods. The details will be presented OLD HEIGHT FOR THE OCCURRENCE and discussed. OF EQUATORIAL SPREAD F DUR- ING MAGNETICALLY DISTURBED PE- TYPE: POSTER RIODS DATE: 2012-03-15 – 17:30 M. K. Madhav Haridas and G. Manju

Vikram Sarabhai Space Centre, India P6.15 GPS POSITIONING DATA ANAL- YSIS AND ITS RELATION TO EQUATO- On the seasonal and solar activity variability RIAL IONOSPHERIC ANOMALIES of threshold height for the occurrence of equa- 1 1 torial spread F during magnetically disturbed Jorge Taramona , Jorge Garcia , and Jorge 2 periods M. K. Madhav Haridas and G. Manju Mirez , Space Physics Laboratory, Vikram Sarabhai 1 Space Centre, Trivandrum – 695 022, Kerala, CORPAC, Lima, Perú 2 India Universidad Nacional de Ingeniería, Lima, Perú Abstract: In this study we are going to analyze GPS During magnetically quiet period, the sea- positioning data obtained from GPS stations in sonal and solar activity variability of the thresh- Peru, they are from LISN (Low Latitude Iono- old height (h’F)c of the base of the F layer, spheric Sensor Network) Project, which is an above which ESF is triggered irrespective of the international distributed observatory to moni- magnitude and polarity of the meridional winds tor the entire atmosphere from Equatorial Re- has been investigated by Manju et al. (2007). gion in South America with the purpose of In the present study, the scope of this work has studying and forecast the Ionospheric anoma- been increased by considering only magnetically lies which aﬀect mainly among others, radio disturbed days, so that the disturbance induced frequency signals, especially GPS signals. They

93 ISEA13 - 13th International Symposium on Equatorial Aeronomy are located near the Equatorial Dip and the signals propagating on long distances within 70° Meridian, where the magnetic inclination the earth-ionosphere waveguide can detect low is almost 0°, which is, in turn, an appropriate ionosphere perturbations as phase variations or condition to study Earth Magnetic Field affect- phase anomalies. Solar flares registered from ing Ionospheric behavior. We have selected 1 April, 2007 to December, 2009 and from Jan- GPS station, namely Puerto Maldonado, which uary to May, 2011 by two SAVNET (South is a station with the most information avail- America VLF Network) radio stations located able. We are going to make a Time Series at Punta Lobos (Peru) and Atibaia (Brazil) are Analysis, tendency, standard deviation and vari- used to study the flare detectability on both ance of those data hourly from one day, then propagation paths. Our results show that the one month, and finally one year. In this case, VLF technique is able to detect very small so- the selected years are 2009,2010 and 2011 al- lar events, making the VLF detection technique though is a short time to determine Ionospheric very promising for the continuous monitoring of Anomalies, because of 11 years solar cycle. It the geospace conditions. is a close approach to assess GPS signals which allow us to monitor the variability of the posi- TYPE: POSTER tioning data and then to estimate the budget DATE: 2012-03-15 – 17:30 error in terms of longitude (meters), and with this data we are going to compare with min- imun required standards stated by OACI in its P6.19 VALIDATION OF THE STORM document 9849 about GNSS Handbook for Air TIME IONOSPHERIC ELECTRIC FIELDS Navigation. The results of this study will allow AND CURRENTS BY USING MAGNETIC us to determine Augmentation Satellite System PERTURBATIONS viability in order to provide safety and efficiency in air navigation service in our region according Naomi Maruyama1, Arthur Richmond2, Astrid to OACI Standards. Maute2, Stan Sazykin3, and Tim Fuller-Rowell1

1 TYPE: POSTER CIRES, University of Colorado Boulder, CO, DATE: 2012-03-15 – 17:30 USA 2 High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA P6.17 SOLAR FLARES DETECTABILITY 3 Rice University, USA USING TWO PARALLEL VLF PROPA- GATION PATHS: NPM-PLO AND NPM- The low and mid latitude ionospheric ATI electrodynamics responds to the balance/imbalance between region 1 and 2 current Edith Macotela1, Jean-Pierre Raulin2, and systems at high latitude that connect the iono- Walter Guevara1 sphere and magnetosphere. The storm time electric field is one of the critical causes of the 1 Comisión Nacional de Investigación y Desar- remarkable plasma variations, such as in the rollo Aeroespacial, Lima, Perú observed global GPS-TEC. There have been a 2 Centro de Radio Astronomía e As- limited number of observations available that trofísica Mackenzie, Universidade Presbiteriana can provide us with a consistent picture of Mackenzie, Brazil the global electric fields and currents during storms. Using a physics based model that elec- Solar flares are among the most important trodynamically couples inner magnetosphere, phenomena which alter the space weather con- ionosphere, plasmasphere, thermosphere, and ditions. These events emit intense X-ray fluxes electrodynamics, we have a capability of pre- that cause perturbations in the ionospheric D- dicting the time variation of the global storm region altering its electrical conductivity. VLF time electric fields and currents including both

94 ISEA13 - 13th International Symposium on Equatorial Aeronomy penetration and disturbance dynamo processes that the mean CNA was more pronounced at that are the two main sources of the mid and SSO, which is the site located nearest to the low latitude storm time electric fields. In this center of the SAMA, but the second highest presentation, we will present a new technique value was found at the farther station. Also, a to validate the modeled electric fields and cur- second order polynomial curve fitting was per- rents by using a network of magnetometers formed in order to establish an empirical rela- from ground and a LEO satellite. tionship between the mean CNA and the total intensity of the geomagnetic field at the riome- TYPE: POSTER ter stations. DATE: 2012-03-15 – 17:30 TYPE: POSTER DATE: 2012-03-15 – 17:30 P6.20 LATITUDINAL DEPENDENCE OF COSMIC NOISE ABSORPTION IN THE IONOSPHERE OVER THE SAMA RE- P6.21 OPERATIONAL IONOSPHERIC GION DURING THE SEPTEMBER 2008 DYNAMICS PREDICTION IN BRAZIL- MAGNETIC STORM IAN SPACE WEATHER PROGRAM 1 1 1 1 Adriano Petry , Jonas Rodrigues De Souza , Juliano Moro , Clezio Marcos De Nardin , 1 1 2 Haroldo Fraga De Campos Velho , André Grahl Mangalathayil Ali Abdu , Emilia Correia , Pereira1, and Graham John Bailey2 Laysa Cristina Araújo Resende1, Lais Maria 1 3 Guizelli , Sony Su Chen , Nelson Jorge 1 Instituto Nacional de Pesquisas Espaciais - 4 5 Schuch , and Kazuo Makita INPE, Sao Jose dos Campos, SP, Brazil 2 University of Sheffield, England, UK 1 Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP, Brazil It is shown the development and preliminary 2 Centro de Radio Astronomía e As- results of operational ionosphere dynamics pre- trofísica Mackenzie, Universidade Presbiteriana diction system for the Brazilian Space Program. Mackenzie, Brazil The system is based on the Sheffield Univer- 3 Universidade de Taubate - UNITAU, Brazil sity Plasmasphere-Ionosphere Model (SUPIM), 4 Southern Regional Space Research Center in a physics-based model computer code describ- collaboration with the LACESM/CT-UFSM, ing the distribution of ionization within the Brazil Earth mid to equatorial latitude ionosphere and 5 Takushoku University, Japan plasmasphere. The model outputs are given in a 2-dimensional plane aligned with Earth mag- In this work we present and discuss some netic field lines, with fixed magnetic longitude results of latitudinal dependence in the cos- coordinate. The code was adapted to provide mic noise absorption (CNA) as observed by the the output in geographical coordinates. It was South American Riometer Network (SARINET) made referring to the Earth"s magnetic field operated in the South American Magnetic as an eccentric dipole, using the approximation Anomaly (SAMA) region, during a moderate based on International Geomagnetic Reference intensity geomagnetic storm that occurred on Field (IGRF-11). During the system operation, September 03, 2008. In our analysis, we used several simulation runs are performed at differ- the data acquired by the imaging riometers in- ent longitudes. The original code would not stalled at São Martinho da Serra (SSO - 29.4º be able to run all simulations serially in reason- S, 53.1º W), Concepcion (CON - 36.5º S, 73.0º able time. So, a parallel version for the code W) and Punta Arenas (PAC - 53.0º S, 70.5º was developed for enhancing the performance. W) and by the single beam riometer installed at After preliminary tests, it was frequently ob- Trelew (TRW - 43.1º S, 65.2º W). A compar- served code instability, when negative ion tem- ison among the selected riometer data showed peratures or concentrations prevented the code

95 ISEA13 - 13th International Symposium on Equatorial Aeronomy from continuing its processing. After a detailed P6.26 GEOMAGNETIC DISTURBANCE analysis, it was verified that most of these prob- AND SOLAR PARTICLE EVENTS AND lems occurred due to concentration estimation THEIR EFFECTS ON THE LOWER of simulation points located at high altitudes, IONOSPHERE, USING SAVNET DATA typically over 4000 Km of altitude. In order to force convergence, an artificial exponential Fernando C. P. Bertoni and Jean-Pierre Raulin decay for ion-neutral collisional frequency was used above mentioned altitudes. This approach Centro de Radio Astronomía e Astrofísica shown no significant difference from original Mackenzie, Universidade Presbiteriana code output, but improved substantially the Mackenzie, Brazil code stability. In order to make operational system even more stable, the initial altitude Measurements performed by the VLF tech- and initial ion concentration values used on nique, using the South America VLF Net- exponential decay equation are changed when work (SAVNET) are presented. The SAVNET convergence is not achieved, within pre-defined project has been involved in the IHY activi- values. When all code runs end, an approxi- ties (2004-2009) and since then in the Inter- mate neighbor searching technique was devel- national Space Weather Initiative (ISWI) pro- oped to obtain the ion concentration values in gram. Explosive solar events and emission a regularly spaced grid, using inverse distance of energetic particles have occurred in Au- weighting (IDW) interpolation. A 3D grid con- gust 2011. The impacts on the upper atmo- taining ion and electron concentrations is gen- sphere were observed through subionospheric erated for every hour of simulated day. Its spa- propagation anomalies as seen in the temporal tial resolution is 1 degree of latitude per 1 de- variations of the signal amplitude and phase gree of longitude per 10 Km of altitude. The recorded on long VLF-paths. In this con- vertical total electron content (VTEC) is calcu- nection, comparing quiet and disturbed days, lated from the grid, and plotted in a geographic the phase exhibited unusual higher values that map. The whole process runs every day and might be associated with excesses of ionization predicts the VTEC values for South America in the lower ionosphere region. These and other region with almost 24 hours ahead. Recently, aspects of these geomagnetic disturbances in data from ionosondes can be assimilated in the the ionosphere will be further discussed. system to improve its accuracy.

TYPE: POSTER TYPE: POSTER DATE: 2012-03-15 – 17:30 DATE: 2012-03-15 – 17:30

96 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 7

NEW TECHNIQUES, EXPERIMENTS, CAMPAIGNS, AND RESULTS

In this session, we solicit papers describing new experimental techniques, experiments, and campaigns, that are, or will be, used to investigate the ionosphere and atmosphere at low latitudes. Examples of new techniques include daytime Fabry-Perot Interferometers (FPI), new radar modes and conﬁgurations, and new types of in situ probes, for example to measure neutral winds on satellites and sounding rockets. We also ask for papers describing new radiowave techniques, such as those that use tomography, GPS, satellite occultations, and beacons, to explore the low latitude ionosphere and upper atmosphere. Ideas for establishing a new heater facility at an equatorial or low latitude site along with optical instruments (daytime FPI, lidars, imagers) are also requested. Presentations are encouraged that show results from new multi-technique clusters and observatory chains that have recently emerged and that promise to reveal new insights regarding atmosphere-ionosphere coupling with both global and regional (i.e., continental) coverage. For example, papers with new results from magnetometer baselines, ionosonde chains, and GPS networks operating at low latitudes are solicited as well as presentations on new satellite or rocket missions, continuous conjugate observations using incoherent scatter radars (AMISR), imagers, and/or networks of instruments.

The session will include results from dedicated observing campaigns, such as those exploring the dynamics of the ionosphere in order to investigate the onset conditions for different types of plasma irregularities and structures which thus shed light on the causes of the day-to-day variability of the ionosphere. Comparative studies between continuous measurements or campaigns conducted at different equatorial regions of the globe (e.g., South America, Africa, India, and the West Pacific) are particularly encouraged. Finally, we request theoretical and modeling presentations that describe how to best use measurements from the new instrumentation and campaigns to further our understanding of the low latitude ionosphere-thermosphere coupling and the generation of plasma structures.

Conveners: R. Pfaﬀ, C. Valladares, and S. Raizada

97 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED – SIGNIFICANT FINDINGS a possible association with atmospheric tides FROM THE C/NOFS SATELLITE MIS- and waves originating from the troposphere. SION As the solar activity increased, the pre-reversal enhancement reappeared and triggered large Odile De La Beaujardiere1, Robert Pfaff2, C. EPBs at dusk. During the night, the satellite S. Huang1, L. Gentile1, P. Roddy1, Y-J. Su1, often flew below the F-region peak. W. Burke3, and J. Retterer3 TYPE: ORAL 1 Air Force Research Laboratory, Space Vehi- DATE: 2012-03-14 – 14:00 cles Directorate, USA 2 NASA Goddard Space Flight Center, Green- INFERRING VERTICAL ION DRIFTS belt, MD, USA FROM INCOMPLETE DATASETS 3 Boston College, MA, USA Russell Stoneback, Nabin Malakar, David Lary, The Communication/Navigation Outage and Roderick Heelis Forecasting System (C/NOFS) satellite was launched in April 2008 into an equatorial or- University of Texas at Dallas, TX, USA bit at altitudes between 400 and 850 km. The The extremely low solar activity during the satellite sensors measure the following: ambi- recent solar minimum of 2007/8 resulted in a ent and fluctuating ion densities; ion and elec- low ion density ionosphere that limited mea- tron temperatures; neutral winds; AC and DC surements of ion drifts by the Ion Velocity Me- electric and magnetic fields, ion drift velocities, ter (IVM) onboard C/NOFS to altitudes near line-of-sight total electron content and iono- perigee. Thus, a full local time description of spheric scintillation. The mission started dur- vertical ion drifts near the equator could only be ing the lowest solar minimum in 100 years. As obtained by averaging over a 67 day period as a consequence, the pre-reversal enhancement perigee precessed through all local times. For in the upward plasma drift, which is responsi- time scales less than 67 days, ion drift data for ble for early evening irregularities and equatorial local times that are not observed are interpo- plasma bubbles (EPBs), was rarely seen. EPBs lated by using Empirical Orthogonal Functions that might be expected in the evening were in- (EOFs). The method decomposes the data into stead observed at the satellite after midnight, a series of orthogonal functions, and retains although UHF ground receivers and ionosondes only few statistically significant EOFs such that continued to detect scintillation in the evening. it could optimally reconstruct the given data. The susceptibility of the ionospheric plasma to The basis functions are not parametric in na- the instabilities that produce irregularities and ture and need not be set a priori, but are objec- EPBs, as determined by models using the am- tively generated by the EOF method using the bient plasma drifts measured by the satellite’s input data. The application of non-parametric, instruments, seems to explain these observa- EOFs to the vertical ion drifts measured by IVM tions. The C/NOFS data seemed to contradict on C/NOFS will be presented. the well-accepted notion that plasma bubbles observed after midnight are dead fossil bub- TYPE: ORAL bles. Other unexpected features are deep de- DATE: 2012-03-14 – 14:20 pletions in the ambient ionosphere observed after midnight and at dawn. These density de- HIGH RESOLUTION IMAGES OF EQUA- creases were sometimes associated with upward TORIAL BUBBLES WITH RADIO BEA- plasma drifts and sometimes downward drifts, CON TOMOGRAPHY and sometimes associated with plasma irregularities and sometimes not. The longitudinal Paul Bernhardt1, Matthew Hei1, Carl and seasonal variability of the ambient density, L. Siefring1, Matthew Wilkens1, Cesar plasma irregularities and ion velocities suggest Valladares2, Jorge Chau3, and Tervor Garner4

98 ISEA13 - 13th International Symposium on Equatorial Aeronomy

1 Naval Research Laboratory, USA SIONS FROM THE C/NOFS SATEL- 2 Boston College, MA, USA LITE: PACIFIC SECTOR 3 Radio Observatorio de Jicamarca, Instituto Roland Tsunoda1, Mamoru Yamamoto2, David Geofísico del Perú, Lima, Perú Bubenik1, and Smitha Thampi3 4 Applied Research Laboratories, University of Texas at Austin, TX, USA 1 SRI International, Menlo Park, CA, USA 2 Research Institute for Sustainable Hu- Using the NRL CERTO beacon on the manosphere, Kyoto University, Japan C/NOFS satellite and an East-West chain of 3 Ahmedabad, India receivers across Peru, electron density maps of equatorial irregularities have been produced The identity of the source mechanism re- showing late time structures in equatorial bub- sponsible for day-to-day variability in the oc- bles. The CERTO beacon radiates coherent currence of plasma structure in the night- frequencies at 150 and 400 MHz with a com- time equatorial F layer, often called equato- mon phase reference. Transmitted continu- rial spread F (ESF), has continued to elude ously from C/NOFS, these signals are phase researchers for more than 50 years. One pos- enhanced after passing through the ionosphere. sibility is that there is still some physics miss- The VHF and UHF signals are acquired using in the paradigm being used to describe this ing NWRA ITS30 receivers and converted into phenomenon. At present, there is a general total electron content with an unknown abso- acceptance that the vigor of the post-sunset lute value using the differential phase technique rise of the F layer is largely responsible for the [Bernhardt and Siefring, 2009]. Receivers lo- development of ESF. The nature of the initial cated at Ancon, Huancayo, Ayacucho, Cuzco, plasma perturbation is considered to be unim- and Puerto Maldonado recorded this relative portant. There is, however, mounting evidence total electron content (RTEC) between the that large-scale wave structure (LSWS), which C/NOFS satellite and the ground. Using an al- appears in the bottomside F layer, is playing gebraic reconstruction technique (ART), tomo- an important, if not central role. Progress in graphic images of equatorial irregularities with this regard has been severely restricted, until 10 km spatial resolution have provided a snap- recently, by the lack of measurements capa- shot of equatorial bubble cross section in elec- ble of detecting and describing LSWS. With tron density. All of the examples of 2-D bubble the launch of a dual-frequency radio beacon images occurred post midnight when they had onboard the Communications/Navigation Out- penetrated to the top-side ionosphere. After age Forecast System (C/NOFS) satellite, it has demonstration of the tomographic imaging ca- become possible, for the first time, to mea- pability, the ground receiver network in Peru sure LSWS properties on a routine basis. In will provide operated to provide routine mea- response to this opportunity, more than 20 surements of the equatorial F-region. ground-based receiving stations have been set up in equatorial regions to create a database Bernhardt, P.A., Siefring, C.L. Low-latitude of LSWS description, which can be used to ad- ionospheric scintillations and total electron dress the seeding question. Instruments such as content obtained with the CITRIS instrument spaced ionosondes and a multi-beam radar have on STPSat1 using radio transmissions from been clustered with the receivers in the Pa- DORIS ground beacons. J. Adv. Space Res. cific sector to expand of the space-time cover- (2009), doi:10.1016/j.asr.2009.12.001 age of LSWS description. These ground-based TYPE: ORAL measurements, combined with the in situ mea- DATE: 2012-03-14 – 14:35 surements from C/NOFS, constitute the most comprehensive diagnostic database for studies specifically directed toward identifying the RESULTS OF CLUSTER EXPERIMENTS source mechanism of the day-to-day variability. USING RADIO BEACON TRANSMIS- Results from combining beacon, ground based,

99 ISEA13 - 13th International Symposium on Equatorial Aeronomy and in situ measurements for some case studies possibilities in investigating the MIT system are will be presented. expected from the ESA Swarm satellite mission. It will consist of 3 spacecraft flying in TYPE: ORAL formation with initial launch altitudes of 450 DATE: 2012-03-14 – 14:50 and 550 km. We will shortly discuss the more than 10 Swarm data products relevant for space science and application that will be provided. INVITED - INVESTIGATING THE LOW LATITUDE IONOSPHERE WITH TYPE: ORAL 10 YEARS OF CHAMP SATELLITE DATE: 2012-03-14 – 15:05 DATA AND PERSPECTIVES FOR THE SWARM SATELLITE CONSTELLATION MISSION INVITED - THE LISN DISTRIBUTED OBSERVATORY - SCIENCE HIGH- Claudia Stolle1, Hermann Lühr2, Nils Olsen1, LIGHTS and Martin Rother2 Cesar Valladares 1 Technical University of Denmark, DTU Space, Denmark Boston College, MA, USA 2 Helmholtz Centre Potsdam, German Re- search Centre for Geosciences, Germany The Low-latitude Ionospheric Sensor Net- work (LISN) is a distributed observatory de- During its 10 years mission the CHAMP signed to nowcast the state and dynamics of the satellite made in situ observations of the mag- low latitude ionosphere and to develop forecasts netic field, electron density and temperature, of the electric fields, densities and equatorial as well as of thermospheric density and zonal spread F (ESF) over the South American conti- winds at altitudes between 300 and 450 km. nent. The LISN observatory includes 3 different Its lifetime from 2000 to 2010 covered the de- types of instruments: GPS receivers, flux-gate cline of the long solar cycle 23. The analysis magnetometers and Vertical Incidence Pulsed of the data revealed many interesting discover- Ionospheric Radar (VIPIR) ionosondes. This ies and contributed significantly to understand report provides a succinct summary of recent the low latitude MIT system. Special profit observations obtained using the LISN GPS re- was obtained by joint analyses with other data ceivers and complemented with measurements and physical models. Examples are: the mass from other instruments and GPS receivers that density anomaly, signatures of upward propa- operate in South America. The observations gating atmospheric waves, magnetic signatures consist of regional maps of TEC values, plots of equatorial plasma irregularities, and the neg- of TEC perturbations across the continent pro- ative solar cycle dependence of the morning duced by the transit of gravity waves and equa- overshoot in electron temperature, just to men- torial plasma bubbles, and plots of scintillation some of them. In this paper we will draw tions in a geographic context. These measure- special attention to the post sunset electron ments indicate that low-latitude GPS stations density and temperature distribution at low lat- can observe TEC enhancements near-midnight itudes. The CHAMP observations reveal an produced by the reverse fountain effect that electron temperature anomaly in analogy to the is driven by localized electric fields and merid- equatorial ionisation anomaly at altitudes below ional winds. Small arrays of GPS receivers can 400 km, although this was not predicted by ear- measure the morphology of gravity waves (GW) lier models. The temperature peaks coincides and together with the LISN GPS network indi- with the density peaks and are increased during cate regions in South America where large GW high solar flux. Its magnitude and global dis- activity occurs. Regional maps of TEC over tribution will be analysed. Even more extended South America have provided the variability of

100 ISEA13 - 13th International Symposium on Equatorial Aeronomy

TEC as a function of local time, season, mag- magnetometer chains in the West African and netic activity, solar cycle and longitude. This East African longitude sectors and compare presentation will also mention other projects these magnetometer-inferred ExB drift veloci- that are being conducted employing electric ties with C/NOFS IVM ExB drift observations. ﬁelds measured with the LISN magnetometer Finally, we theoretically model the ionospheric baselines and the LISN VIPIR ionosonde. response to these sharp longitude gradients using the Global Ionosphere Plasmasphere (GIP) TYPE: ORAL time-dependent model. We present the obser- DATE: 2012-03-14 – 15:25 vational ExB drift results and the calculated electron density distributions and suggest future studies that would be able to account for DETERMINING THE SHARP, LONGITU- such sharp gradients in ExB drift velocities at DINAL GRADIENTS IN EQUATORIAL the boundaries of the 4-cell structures. EXB DRIFT VELOCITIES ASSOCIATED WITH THE BOUNDARIES OF THE 4- TYPE: ORAL CELL, NON-MIGRATING STRUCTURES DATE: 2012-03-14 – 15:45

David Anderson EQUATORIAL IONOSPHERIC DENSITY CIRES, University of Colorado Boulder, CO, DISTRIBUTION AND THE CORRE- USA SPONDING ELECTRODYNAMICS DIF- FERENCE BETWEEN AFRICAN AND Previous studies have established the exis- SOUTH AMERICAN SECTORS tence of a 4-cell, longitude pattern in equatorial F region ionospheric parameters such as TEC Endawoke Yizengaw1, Eftyhia Zesta2, Mark and electron densities and in daytime, equato- Moldwin3, Baylie Damtie4, Cesar Valladares1, rial ExB drift velocities. A recent paper, for and Robert Pfaff5 the first time, quantified the longitude gradients in ExB drift associated with the 4-cell 1 Boston College, MA, USA tidal structures and confirmed that these sharp 2 Air Force Research Laboratory, USA gradients exist on a day-to-day basis. Using 3 Department of Atmospheric, Oceanic and the Ion Velocity Meter (IVM) on the Commu- Space Sciences, University of Michigan, MI, nication/Navigation Outage Forecast System USA (C/NOFS) satellite to obtain daytime, verti- 4 Bahir dar University, Ethiopia cal ExB drift velocities, it was found, for ex- 5 NASA Goddard Space Flight Center, Green- ample, that for October 5, 6 and 7, 2009 in belt, MD, USA the Atlantic sector, the ExB drift velocity gradient was about 1m/sec/degree. For March The uneven distribution of ground-based 23, 24 and 25, 2009 in the Peruvian sector, it instruments in the equatorial regions hinders was about -4m/sec/degree. In this paper we our ability to obtain a global understanding present results from a multi-instrument study of the dynamics and structure of the equa- of the sharp longitude gradients in the day- torial ionosphere. In Africa, which has been time ExB drift velocities at the boundaries of mostly devoid of ground-based instruments, the each of the 4-cell, non-migrating structures. ionospheric density structure has been tradi- We utilize both the C/NOFS IVM observa- tionally estimated by model interpolation over tions of ExB drift velocities and the ground- vast geographic areas, and that make difficult based magnetometer-inferred ExB drift veloc- for the communication and navigation systems ities. We incorporate the LISN (Low-latitude operating in the region. Recent ground- and Ionospheric Sensor Network) magnetometer space-based observations have shown that ge- chains in the South American sector and the omagnetic storms can have dramatic longitu-

101 ISEA13 - 13th International Symposium on Equatorial Aeronomy dinal differences in equatorial ionospheric elec- (C/NOFS) satellite, post-midnight plasma den- trodynamics, such as enhanced generation of sity irregularities have frequently been detected F-region plasma irregularities, and super foun- in the low-latitude region during the present tain effect at low latitudes. The vertical struc- solar minimum period. Using the 47-MHz tures of the equatorial density distribution can Equatorial Atmosphere Radar (EAR) in West be reconstructed by applying tomographic re- Sumatra, Indonesia (10.36S dip latitude), it construction technique on the ground-based is shown that the post-midnight irregularities GPS TEC and occultation TEC from GPS re- observed with the EAR are different from stan- ceivers’ onboard LEO satellites. One of the dard irregularities typically observed near the possible driving mechanisms that govern the magnetic equator but instead, are quite sim- equatorial electrodynamics is the vertical drift, ilar to those observed with the MU radar in which strongly affects the structure and dynam- midlatitude (29.3N dip latitude). Utilizing ics of the ionosphere in the low/mid-latitude rapid beam-steering capability of the EAR, region. According to the observations per- it is found that their tilted spatial structures formed at different longitudes, using recently are the same as medium-scale traveling iono- deployed limited ground-based instruments, the spheric disturbances (MSTIDs) which are fre- vertical drift velocities and the vertical density quently observed in midlatitude, and they usu- distributions have significant longitudinal dif- ally propagate westward as opposed to typical ferences. This paper presents tomographically plasma depletions that propagate eastward ob- reconstructed density distribution and the cor- served in the post-sunset period. The zonal responding vertical drifts observed at three dif- and meridional ExB drift velocities measured ferent longitudes: East African, West African, by C/NOFS are consistent with the westward and West American sectors. The vertical drift propagation of backscatter echoes and the line- is estimated using pairs of ground-based mag- of-sight Doppler velocities observed with the netometers technique. EAR, respectively. The density structures and EAR echo intensity do not show a clear correla- TYPE: ORAL tion, but some echoes are observed at the edge DATE: 2012-03-14 – 16:00 of density depletions, which may be a manifestation of a secondary ExB instability to produce 3-m scale irregularities. During solar minimum, POST-MIDNIGHT IONOSPHERIC IR- the nighttime zonal drift could be reversed from REGULARITIES OBSERVED WITH THE eastward to westward with increasing altitude C/NOFS SATELLITE AND THE EQUA- because of very low Pedersen conductivity in TORIAL ATMOSPHERE RADAR (EAR) the F region, which could explain the high occurrence of midlatitude-type irregularities in Tatsuhiro Yokoyama1, Robert Pfaff2, Patrick the low-latitude region that is connected with A. Roddy3, Mamoru Yamamoto1, and Yuichi the topside equatorial ionosphere. Otsuka4 TYPE: ORAL 1 Research Institute for Sustainable Hu- DATE: 2012-03-14 – 16:15 manosphere, Kyoto University, Japan 2 NASA Goddard Space Flight Center, Green- belt, MD, USA THE NEW EMBRACE MAGNETOME- 3 Air Force Research Laboratory, Space Vehi- TER NETWORK IN SOUTH AMERICA cles Directorate, USA 4 Solar-Terrestrial Environment Laboratory, Clezio Marcos De Nardin1, José Ricardo Nagoya University, Japan Abalde2, S. S. Chen1, Lais Maria Guizelli1, Laysa Cristina Araújo Resende1, Juliano Moro1, Since the launch of Communica- Antonio L. Padilha 1, Paulo Fagundes2, E. tion/Navigation Outage Forecasting System Correia1, N. J. Schuch1, S. Domingos1, W. S.

102 ISEA13 - 13th International Symposium on Equatorial Aeronomy

C. Borges1, F. P. V. Mesquita1, Avicena Filho1, tracking subionospheric propagation anomalies A. Cunha-Neto1, C. Castilho1, W. Gargarela appears as a very promising tool to study var- Jr1, and R. A. A. Lima1 ious aspects of Space Weather disturbances. On long timescales it is possible to indirectly 1 Instituto Nacional de Pesquisas Espaciais - monitor the solar Lyman-? radiation along the INPE, Sao Jose dos Campos, SP, Brazil solar cycles. Short time phenomena like solar 2 Universidade do Vale do Paraíba, Sao Jose explosive events can be observed with 100% dos Campos, Brazil probability, even for the small intensity events. Finally, the same technique is relevant to study We present the new EMBRACE Magne- the low ionospheric perturbations caused by ge- tometer Network in South America, which omagnetic storms on typical timescales of a day so far is planned to cover most of the to few days. Easter Southern American longitudinal sector displacing magnetometer in Belem-PA TYPE: ORAL (BLM, 01°26’28" S, 48°26’40" W), Manaus- DATE: 2012-03-14 – 16:45 AM (MAN, 02°54’52" S, 59°59’40" W), Sao Luis-MA (SLZ, 02°35’36" S, 44°12’43" W), Eusebio-CE (EUS, 03°52’48 S, 38°25’28" W), TID STUDIES IN PERU WITH THE TID- Palmas-TO (PAL, 10°17’50" S, 48°21’41" DBIT HF DOPPLER SOUNDER

W), Cachoeira Paulista-SP (CXP, 22°42’07 S, 1 1 45°00’52 W), Sao Jose dos Campos-SP (SJC, GeoﬀCrowley , Adam Reynolds , Fabiano Rodrigues1, Rick Wilder1, Jorge Chau2, and 23°12’38" S, 45°57’23 W), Sao Martinho da 2 Serra-RS (SMS, 29°26’36" S, 53°49’22" W), Otto Castillo and the Brazilian Antarctic Station - Fer- 1 Atmospheric and Space Technology Research raz, King George Island (FRZ, 62°05’06" S, Associates, Boulder, CO, USA 58°24’12" W). We discuss the purpose and sci- 2 Radio Observatorio de Jicamarca, Instituto entiﬁc goals of the network. We provide details Geofísico del Perú, Lima, Perú on the instrumentation, the inter-calibration procedure, and installations of equipments al- HF Doppler sounders represent a low-cost ready interlaid. In addition, we present and dis- and low-maintenance solution for monitoring cuss details on the data storage, near-real time wave activity in the F-region ionosphere. HF display and availability. Doppler sounders together with modern data analysis techniques provide both horizontal and TYPE: ORAL vertical TID velocities and wavelengths across DATE: 2012-03-14 – 16:30 the entire spectrum from periods of 1 min to over an hour. ASTRA has developed a new system called "TIDDBIT" (TID Detector Built In THE SOUTH AMERICA VLF NET- Texas), and data will be presented from TID- WORK (SAVNET): PROVIDING NEW DBIT systems in Texas, Virginia, and Peru. We GROUND-BASED DIAGNOSTICS OF show how the completeness of the wave in- SPACE WEATHER CONDITIONS formation obtained from these systems makes Jean-Pierre Raulin it possible to reconstruct the vertical displacement of isoionic contours over the 200 km Centro de Radio Astronomía e Astrofísica horizontal dimension of the sounder array. The Mackenzie, Universidade Presbiteriana TIDDBIT Sounder was recently deployed in Ji- Mackenzie, Brazil camarca, Peru. Results from the Jicamarca site will be shown and compared with the sounder In this paper we present recent results ob- data from other locations. The TIDDBIT sys- tained by the South America VLF Network tem in Peru detected atmospheric waves gen- (SAVNET). The use of the VLF technique by erated by the Japanese earthquake/tsunami in

103 ISEA13 - 13th International Symposium on Equatorial Aeronomy

March 2011. Spread-F conditions detected by DRIFTS, DENSITIES AND TEMPERA- TIDDBIT are also compared with GPS scin- TURES AT JICAMARCA tillation detected by ASTRA’s CASES dual- 1 2 2 frequency receiver in Jicamarca. Marco Milla , Erhan Kudeki , Pablo Reyes , and Jorge Chau1 TYPE: ORAL 1 Radio Observatorio de Jicamarca, Instituto DATE: 2012-03-15 – 08:00 Geofísico del Perú, Lima, Perú 2 University of Illinois at Urbana-Champaign, Urbana, IL USA 24-HR THERMOSPHERIC WINDS MEA- SURED DURING THE 2011 COR- At Jicamarca, standard incoherent scatter RER CAMPAIGNS: COMPARISONS TO radar experiments were typically classiﬁed in CHAMP AND WINDI CLIMATOLOGIES two groups, perpendicular and oblique modes, AND THE IMPACTS ON PBMOD ESF depending on whether the beam was pointed FORECASTS perpendicular to the Earth’s magnetic ﬁeld (B) or away from this direction. When the beam is Andrew Gerrard1, Erick Vidal Safor2, and John 3 pointed perpendicular to B, very accurate es- Meriwether timates of F-region plasma drifts can be ob-

1 tained, while, measurements of plasma densi- New Jersey Institute of Technology, The Cen- ties and temperatures were usually obtained us- ter for Solar-Terrestrial Research, NJ, USA ing oblique beams. Recently, taking advantage 2 Instituto Geofísico del Perú, Lima, Perú 3 of the modularity of the Jicamarca antenna ar- Physics and Astronomy, Clemson University, ray, we have implemented a new incoherent Clemson, SC, USA scatter radar mode in which the ionosphere is probed using multiple beams pointing into dif- In this paper we present both night and ferent directions. In this way, different modes day thermospheric wind observations made of magneto-ionic propagation and regimes of with the Second-generation, Optimized, Fabry- the incoherent scatter signals are excited. By Perot Doppler Imager (SOFDI), a novel triple- forward-modeling the signals measured by the etalon Fabry-Perot interferometer (FPI) de- different beams, we can maximize the number signed to make 24-hour measurements of ther- of ionospheric physical parameters that can be mospheric winds from OI 630-nm emission. inverted simultaneously. In this work, we report These results were obtained from under the on the description of this new mode of opera- magnetic equator at Huancayo, Peru during the tion, the construction of the forward-model of summer 2011 CORRER Campaigns. The ther- the measured signals and the inversion proce- mospheric wind measurements from Huancayo dure applied to the computation of the iono- replicate recently reported CHAMP zonal winds spheric parameters. A detailed analysis of the measurements during daytime periods; in dis- accuracy of the estimated plasma parameters is agreement with current empirical daytime wind presented and compared to measurements car- climatologies. These differences are discussed ried out using standard experiments. Applying in light of recent ESF formation theories. this technique, the simultaneous estimation of plasma drifts, densities, and temperatures is fi- TYPE: ORAL nally possible at Jicamarca. DATE: 2012-03-15 – 08:15 TYPE: ORAL DATE: 2012-03-15 – 08:30 STATUS REPORT ON MULTI-BEAM IN- COHERENT SCATTER RADAR MEA- SUREMENTS FOR THE SIMULTA- A TWO-DIMENSIONAL APPROACH NEOUS ESTIMATION OF F-REGION FOR FABRY-PEROT INTERFEROME-

104 ISEA13 - 13th International Symposium on Equatorial Aeronomy

TER IMAGE ANALYSIS: MODELING, Juha Vierinen FILTERING, AND PARAMETER ESTI- MATION Sodankyla Geophysical Observatory, Finland We present a novel dual-polarisation in- Luis Navarro1, Marco Milla1, Paul Rodriguez2, coherent scatter radar analysis method called and Jorge Chau1 Faraday rotation lag-profile inversion. In addition to estimating the plasma backscatter au- 1 Radio Observatorio de Jicamarca, Instituto tocorrelation function at each height, the prop- Geofísico del Perú, Lima, Perú agation delay between the two different charac- 2 Sección de Ingeniería Electrónica, Pontificia teristic modes of propagation can be measured, Universidad Católica del Perú, Lima, Perú which allows the absolute electron density to be measured independently of the target backscat- In Aeronomy, Fabry-Perot interferometers ter mechanism. The method has recently been are used to detect the airglow emissions from demonstrated a Jicamarca as a part of a general the Earth’s upper atmosphere. By analyzing purpose experiment, which allows the simul- the measured interferometric ring patterns, it taneous measurement of the full atmospheric is possible to determine the Doppler shift and profile, including everything between the MST- spectral broadening of the airglow signals, and region and the exosphere. then obtain estimates of the neutral winds and temperatures of the upper atmosphere. Stan- TYPE: ORAL dard procedures collapse the interferometric DATE: 2012-03-15 – 09:00 images in a single dimension before applying any parameter estimation technique, this procedure, however, disregards possible distortions THE ROLE OF OPTICALLY-THIN AND of the images due to misalignment of the op- BRAGG SCATTERING IN RADAR ME- tic devices. A new procedure is been devel- TEORS oped that analyzes directly the images in two John Mathews dimensions without any previous manipulation of the original data. We first notice that the Pennsylvania State University, State Park, PA, acquired interferometric patterns are corrupted USA with Speckle (multiplicative) noise; therefore, as a pre-processing step, we denoise the images Radar meteor head- and trail-echoes have via a Speckle Total Variation model. Then, been variously described as “overdense” ver- we proceed to fit the noise-free images using a sus “underdense” (relative to plasma frequency) Fourier model of the interferometric ring pat- and, additionally, in terms of Bragg scattering. terns, to finally assess the winds and temper- We argue that optically-thin, coherent scatter- atures in the upper atmosphere. Our prelim- ing is largely sufficient to describe radar me- inary results show that the proposed method teor observations and that, while appropriate gives superior parameter estimation for both to volume filled incoherent scattering, Bragg synthetic and real images than the standard scattering is of limited use in interpretation of procedures; moreover, we also present a de- radar meteors. We present a relatively strict tailed analysis of the expected error in our es- definition of optically-thin coherent scattering timations. in terms of the net scattered E-field in the plasma relative to the incident E-field and note TYPE: ORAL that the optically-thin scattering occurs even in DATE: 2012-03-15 – 08:45 cases of small—volume limited—plasmas that are strictly “overdense”. We give modeling examples supporting this approach and note FARADAY ROTATION LAG-PROFILE that, beyond meteors, radar phenomena such INVERSION AT JICAMARCA as 150 km echoes and PMSE may be the result

105 ISEA13 - 13th International Symposium on Equatorial Aeronomy of radar scattering from limited ensembles of ability to temporarily control the RF propaga- highly localized plasma features. tion environment through an on-demand mod- iﬁcation of the ionosphere. Among the many TYPE: ORAL questions this experiment is designed to inves- DATE: 2012-03-15 – 09:15 tigate is whether an artiﬁcially generated local enhancement to the E-region conductivity will result in a regional suppression of scintillation? SPACE PLASMA ON DEMAND – MOD- IFICATION OF THE IONOSPHERIC TYPE: ORAL RF PROPAGATION ENVIRONMENT DATE: 2012-03-15 – 09:30 THROUGH CHEMICAL RELEASES

Ronald Caton COLLABORATIVE NETWORK FOR Air Force Research Laboratory, USA OBSERVATION OF TRANSIENT LU- MINOUS EVENTS, IN BRAZIL AND The Air Force Research Laboratory will WHOLE LATIN AMERICA conduct an experiment on the artificial generation of ionization clouds with heavy metal Fernanda São Sabbas vapor releases in the ionosphere from sounding rockets. The Metal Oxide Space Cloud ex- Instituto Nacional de Pesquisas Espaciais - periment (MOSC) consists of multiple rocket INPE, Sao Jose dos Campos, SP, Brazil launches from the Kwajalein Atoll with releases of samarium vapor near 200 km and 130 km. Transient Luminous Events – TLEs, are The exothermic reaction of vaporized samar- the optical effect of lightning discharges in ium metal with background oxygen atoms will the upper atmosphere above thunderclouds. create a long-lived and localized plasma cloud: They were discovered in 1989 when sprites, Sm + O ? SmO+ + e -. In at least two previ- the most spectacular of these events, were ous experiments, samarium gas releases in the recorded for the first time in the United States ionosphere have shown evidence of significant with a low-light-level video camera. Sprites ionization; however, no direct measurements of are reddish optical emissions, mainly from the the densities were made. The primary objective N2 (1PG) band, emitted by the mesospheric of MOSC is to fully characterize the physical, plasma streamers that form them and initiate spectral and plasma density composition of the at 75 km. These plasma channels propagate artificial plasma as a function of release alti- upwards to the bottom of the nighttime iono- tude and time. In addition to samarium canis- sphere ( 90 km) and downwards to 30 km, last- ters, the rocket payload will include a Coherent ing 5-300 ms. Other TLEs include Blue Jets, Electromagnetic Radio Tomography (CERTO) plasma streamers that propagate from the top beacon with ground observing sites arranged for of thunderstorms up to 40 km, Gigantic Jets, best reception of the signal through the cloud. that start as Blue Jets but propagate up to 90 Incoherent scatter probing of the ionization km and exhibit sprite-like shapes on the top 50 cloud with the ALTAIR radar facility will pro- km, Elves, sub-ms optical enhancements of the vide electron densities. GPS scintillation and ionosphere at an altitude of 100 km, and Halos, TEC receivers will be collocated with All-Sky disk shaped optical emission produced by the Imagers and HF receive equipment designed to same physical process that generates sprites. monitor oblique returns from a digisonde on Observations obtained from the Space Shuttle, the island of Roi-Namur. An optical spectro- and during ground and aircraft campaigns con- graph will provide details on the spectral char- ducted in the U.S., Peru, Central America, Aus- acteristics of the plasma cloud. Results will be tralia, Japan, Europe, Taiwan, and Brazil have used to improve existing models and tailor fu- confirmed the global aspect of TLEs. Since ture experiments targeted at demonstrating the 2002, five different field campaigns have been

106 ISEA13 - 13th International Symposium on Equatorial Aeronomy performed in Brazil to make TLE observations. to determine how the plasma irregularities af- The first campaign was in 2002/2003, and the fect the propagation of electromagnetic waves. others occurred once a year starting in 2005. The satellite was launched in April, 2008 into More than 700 events, mainly sprites, have a low inclination (13?), elliptical (? 400 x been recorded over South American thunder- 850 km) orbit. The satellite sensors mea- storms during the Brazilian campaigns so far. sure the following parameters in situ: ambi- This paper will review the main concepts re- ent and fluctuating electron densities, AC and lated to these phenomena, their generation, DC electric and magnetic fields, ion drifts and possible effects in the upper atmosphere and large scale ion composition, ion and electron observations in Brazil. It will also show the temperatures, and neutral winds. C/NOFS current state of a network of cameras in the is also equipped with a GPS occultation re- process of being installed in Brazil for contin- ceiver and a radio beacon. In addition to the uous observation of TLE. The steps to form a satellite sensors, complementary ground-based collaborative Latin-American network for TLE measurements, theory, and advanced modeling observation will also be discussed. techniques are also important parts of the mission. We report scientific and space weather TYPE: ORAL highlights of the mission after nearly four years DATE: 2012-03-15 – 09:45 in orbit.

TYPE: POSTER P7.01 AN OVERVIEW OF SCIEN- DATE: 2012-03-15 – 17:30 TIFIC AND SPACE WEATHER RE- SULTS FROM THE COMMUNICA- TION/NAVIGATION OUTAGE FORE- P7.02 PRELIMINARY RESULTS AND CASTING SYSTEM (C/NOFS) MISSION COMPARISON OF TWO METEOR RADARS AT 40 MHZ AND 50 MHZ AT Robert Pfaﬀ1, Odile De La Beaujardiere2, Don- JICAMARCA RADIO OBSERVATORY ald Hunton3, Roderick Heelis4, Greg Earle5, Paul Strauss6, and Paul Bernhardt7 Luis Condori, Karim Kuyeng, Rita Abad, and Jorge Chau 1 NASA Goddard Space Flight Center, Green- belt, MD, USA Radio Observatorio de Jicamarca, Instituto Ge- 2 Air Force Research Laboratory, Space Vehi- ofísico del Perú, Lima, Perú cles Directorate, USA 3 JASMET (a 50MHz Meteor Radar) has Air Force Research Laboratory, USA been operating at Jicamarca Radio Observa- 4 University of Texas at Dallas, TX, USA 5 tory since 2006 helping us in the studies of the Virginia Polytechnic Institute and State Uni- Mesosphere and Lower Thermosphere dynam- versity, Blacksburg, VA, USA ics. Recently(end of 2011), we have deployed 6 The Aerospace Corporation, USA 7 a new 42.5MHz Meteor Radar at the same Naval Research Laboratory, USA location. This presentation reports the pre- The Communication/Navigation Outage liminary results of simultaneous measurements Forecasting System (C/NOFS) Mission of the conducted by Jicamarca staﬀ. We have ob- Air Force Research Laboratory is described. tained interesting results that will be the core C/NOFS science objectives may be organized for this presentation. We will also present the into three categories: (1) to understand phys- future plans for these meteor radars. ical processes active in the background iono- Key words: Meteor Radar sphere and thermosphere in which plasma instabilities grow; (2) to identify mechanisms TYPE: POSTER that trigger or quench the plasma irregulari- DATE: 2012-03-15 – 17:30 ties responsible for signal degradation; and (3)

107 ISEA13 - 13th International Symposium on Equatorial Aeronomy

P7.05 ON THE CHARACTERIZATION Radio Observatorio de Jicamarca, Instituto Ge- OF RADAR RECEIVER SYSTEMS FOR ofísico del Perú, Lima, Perú METEOR-HEAD STUDIES For ISR campaigns, for many years the Jica- 1 1 2 Freddy Galindo , Julio Urbina , Jorge Chau , marca Radio Observatory (JRO) had to choose 3 2 Lars Dyrud , and Marco Milla between getting Drifts (East West Drift mode) or getting electron densities, composition and 1 Communications and Space Sciences Labora- temperatures (Double Pulse Faraday mode / tory, Pennsylvania State University, University Hybrid 2 mode) in order to fulfill the require- Park, PA, USA ments of ISCOD experiments and other scien- 2 Radio Observatorio de Jicamarca, Instituto tists. Since July 2011, a new operation mode Geofísico del Perú, Lima, Perú started. This new mode is able to get elec- 3 Applied Physics Laboratory, John Hopkins tron densities, composition, temperatures and University, MD, USA drifts simultaneously. For CSR campaigns a We discuss the influence that radar receiver new mode have been running since 2010, the systems play on the determination of Signal new JULIA EW + Imaging is a combination of to Noise Ratio (SNR) that are obtained from a modified old Julia EW mode with an Imaging meteor-head returns due to intrinsic physical mode allowing us to get ESF images every night properties of these echoes. This influence is during this mode. In this poster we will present described by expressing the radar equation for results of the new ISR mode obtained during meteor-head echoes in terms of the ambigu- two long campaigns and comparisons with re- ity function of the transmitter pulse envelope sults of previous modes. And for the new CRS and the filter response of the radar receiver. mode we will present results and statistics ob- As result of this relationship, SNR values from tained. meteor-head echoes will exhibit temporal fluctuations, at any Doppler velocity. Furthermore, Key words: ISR, measured parameters on we present meteor radar data collected using an ISR, CSR,ESF the 50 MHz antenna array located at Jicamarca Observatory (JRO) to illustrate the theoretical TYPE: POSTER findings of our analysis. We demonstrate the DATE: 2012-03-15 – 17:30 importance of characterizing radar systems to correctly determine SNR values from meteor- P7.08 CONJUGATE OBSERVATIONS OF head echoes and consequently infer unbiased IONOSPHERIC PROCESSES IN THE meteor parameters that are derived using SNR AMERICAN SECTOR profiles. We also show a statistical analysis that reveals that at least 14% of the population col- Carlos Martinis1, JeffBaumgardner1, Clau- lected each day at JRO exhibit these temporal dio Brunini2, Terry Bullet3, Erika Gularte 2, fluctuations on SNR plots, and therefore any Diego Janches4, Michael Mendillo1, and Paul approach (e.g. inversion techniques) must in- Zablowski1 clude a correction procedure to correctly infer meteor parameters from these subset of events. 1 Boston University, MA, USA 2 Universidad Nacional de la Plata, Argentina TYPE: POSTER 3 University of Colorado Boulder, CO, USA DATE: 2012-03-15 – 17:30 4 NASA Goddard Space Flight Center, USA

P7.07 LONG-TERM ISR AND CSR CAM- The American sector at low-middle lati- PAIGNS tudes in the southern hemisphere presents some peculiarities like the South Atlantic Magnetic Karim Kuyeng, Luis Condori, Percy Condor, anomaly and sharp deviations between geomag- Miguel Urco, Marco Milla, and Jorge Chau netic and geographic latitudes. This makes

108 ISEA13 - 13th International Symposium on Equatorial Aeronomy a unique region regarding the dynamics and developing multi-instruments gondola for the electrodynamics of the upper atmosphere. Ini- CNES balloon flights in equatorial, mid-latitude tial optical observations from all-sky imagers at stratosphere. The idea is to carry in-situ ob- Arecibo, Puerto Rico (18.3N, 66.7W, + 28mag servations of lightning and associated strato- lat) and Mercedes, Argentina (34.6S, 59.4W, spheric discharges (TLEs blue jets, elves, - 24.5mag) show phenomena that can be ex- etc.) simultaneously and in conjunction with plained only through an electrodynamical cou- the satellite observations in the ionosphere. pling between both hemispheres. Coupling be- For this purpose we are developing a multi- tween local E and F regions seems to play a instruments autonomous gondola for the bal- crucial role in some of the processes observed. loon flights with low power instruments that Thus a proper understanding of the forma- required high data rate acquisition and accu- tion and evolution of these low and midlatitude rate dating. The LATMOS EF-ATLEC gon- processes needs our knowledge of parameters dola consists of the electric field instrument at both hemispheres and at both ionospheric SDA (DC-few kHz), photometers, 3D cameras, heights. We present results from ionosonde sound recorder. The concept of this gondola is observations from the USGS San Juan Obser- planned to be used by other high data rate in- vatory (18.11N, 66.15W) and La Plata (34.9S, struments on Cobrat/Taranis balloon project, 57.9W), near the Arecibo and Mercedes Obser- like search-coil magnetometers and gamma de- vatories, respectively, as well as TEC and phase tector. Preliminary tests of multi-instruments fluctuations observations from GPS receivers gondola with two onboard instruments (SDA collocated with the radio and optical instru- of LATMOS and Field Mill of SPRL/Michigan) ments. This setting allows the measurement were performed in 2011 during CNES campaign of local and magnetically conjugate ionospheric in Kiruna/Sweden. Results and future develop- parameters. These studies are performed in the ments are discussed. framework of AIRES (Argentina Ionospheric Radar Experiment Station) and represent the TYPE: POSTER initial attempts toward a comprehensive under- DATE: 2012-03-15 – 17:30 standing of thermosphere-ionosphere processes at low-middle latitudes measured by clusters and networks of instruments. P7.10 THE EFFECTS OF COULOMB COLLISIONS ON H+, HE+, AND O+ TYPE: POSTER PLASMAS FOR INCOHERENT SCAT- DATE: 2012-03-15 – 17:30 TER RADAR APPLICATIONS AT JICA- MARCA P7.09 EF-ATLEC MULTI-INSTRUMENTS 1 2 1 GONDOLA Marco Milla , Erhan Kudeki , and Jorge Chau

Michel Godefroy and Elena Seran 1 Radio Observatorio de Jicamarca, Instituto Geofísico del Perú, Lima, Perú CNRS-LATMOS, France 2 University of Illinois at Urbana-Champaign, Urbana, IL USA EF-ATLEC multi-instruments gondola for balloon flights in stratosphere in conjunction with satellite TARANIS mission" The need for considering the effects of Coulomb collisions in modeling the spectrum MG & ES /LATMOS measurements at Jicamarca was first suggested by Sulzer and González [1999]. Motivated by In frame of preparation of TARANIS mis- this work, Milla and Kudeki [2011] developed a sion (CNES micro-satellite; launch: 2015; collisional spectrum model that takes into ac- geosynchronous orbit at 700 km) we are count Coulomb collision effects at all magnetic

109 ISEA13 - 13th International Symposium on Equatorial Aeronomy aspect angles including the direction perpen- TYPE: POSTER dicular to B as needed for Jicamarca applica- DATE: 2012-03-15 – 17:30 tions. The model has been applied in preliminary fittings of radar data providing encouraging results. However, the model was de- P7.11 TOMOGRAPHIC IMAGING veloped only for O+ plasmas, which limits its OF THE EQUATORIAL AND LOW- application to F-region measurements between LATITUDE IONOSPHERE OVER 200 km and 600 km. As an extension of this CENTRAL-EASTERN BRAZIL work, we are in the process of developing a new multi-component collisional incoherent scatter Marcio Muella1, Eurico De Paula2, Cathryn spectrum model that considers O+, H+, and Mitchell3, Ricardo Paes2, and Inez Staciarini He+ plasmas as needed for perpendicular-to-B Batista2 radar observations at Jicamarca. The develop- 1 ment of the spectrum model is being carried Universidade do Vale do Paraíba, Sao Jose out based on the simulation of charged parti- dos Campos, Brazil 2 cle trajectories embedded in a collisional mag- Instituto Nacional de Pesquisas Espaciais - netized plasma. In our approach, friction and INPE, Sao Jose dos Campos, SP, Brazil 3 diffusive forces model the effects of Coulomb University of Bath, England, UK collisions on the particle motion; the expected values of these forces are taken from the stan- A four-dimensional time-dependent tomo- dard Fokker-Planck model of Rosenbluth et al. graphic algorithm, named Multi Instrument [1957]. Since the simulation process is a very Data Analysis System (MIDAS), is used to im- demanding computational task, we have devel- age the equatorial and low-latitude ionosphere oped a CUDA-based simulation program in or- over the central-eastern sides of the Brazil- der to run the simulations in an NVidia Tesla ian territory. From differential phase data ob- GPU system. The detailed study of the statis- tained by a chain of ground-based GPS re- tics of the simulated trajectories will give us ceivers the total electron content (TEC) is es- further insight into the physics of Coulomb col- timated and then, together with a modeled lisions, which is needed for the interpretation ionosphere from International Reference Iono- of incoherent scatter measurements. For in- sphere (IRI) model, the electron density distri- stance, we have found that the motion process bution is reconstructed and the parameters of of the ions can be approximated as a standard the F2-peak layer are accessed from the images. Brownian motions process, and thus analytical This paper presents the first study of iono- expressions for ion statistics functions can be spheric tomography using real dual-frequency determined. On the other hand, in the case data from the Brazilian Network for Continuous of the electrons, their motion is more compli- GPS Monitoring (RBMC). Ionospheric F2-peak cated than a Brownian process and requires electron density (NmF2) accessed from the im- a detail analysis, however, a simplification is ages are compared to concurrent measurements possible since the characteristics of the elec- from three ionosondes installed across Brazil. tron motion are independent from the type of One year of data during the solar maximum plasma considered. In this presentation, we will period from March/2001 to February/2002 is report on our advances on the development of used to analyze the seasonal and hourly varia- this new spectrum model. The model will be tion of the F2-layer peak density. The accuracy used in the simultaneous estimation of drifts, with which MIDAS images the electron den- densities, and temperatures of the equatorial sity during geomagnetic quiet periods is investi- ionosphere in perpendicular-to-B experiments gated through its correlation and deviation with at Jicamarca. This experimental evaluation will the ionosonde and IRI model data, respectively. have a broader impact since the accuracy of the The main aspects of the reconstruction results Fokker-Planck collision model will be tested. at the equatorial ionization anomaly (EIA) region over Brazil are presented.

110 ISEA13 - 13th International Symposium on Equatorial Aeronomy

TYPE: POSTER P7.13 PARTICLE IMAGE VELOCIME- DATE: 2012-03-15 – 17:30 TRY (PIV) MEASUREMENTS OF THE VECTOR VELOCITY OF EQUATORIAL SPREAD F IRREGULARITIES OVER JI- P7.12 INVESTIGATION OF LOW- CAMARCA LATITUDE IONOSPHERE OVER CHINA WITH A TWO-MODE VHF RADAR Miguel Urco and Jorge Chau Radio Observatorio de Jicamarca, Instituto Ge- Baiqi Ning1, Guozhu Li2, and Lianhuan Hu2 ofísico del Perú, Lima, Perú 1 Beijing National Observatory of Space Envi- Since the first report made in 1938, Equa- ronment, Institute of Geology and Geophysics, torial Spread F (ESF) has been observed with Chinese Academy of Sciences, Beijing, China great interest. At Jicamarca, this phenomenon 2 Institute of Geology and Geophysics, Chinese has been observed continuously by the main Academy of Sciences, China radar operating in the CSR (Coherent Scat- ter Radar) mode since 1996 and recently a A 47.5 MHz VHF radar with a peak power new mode of operation, called JULIA Imaging, of 24 kW has been set up at Sanya (18.3° N, have been implemented. This new mode pro- 109.6° E, dip latitude 12.8°N), China in 2009. vides ESF data with high resolution in altitude, The most important feature is that the radar space, and time. In this work, taking advantage can work alternately in coherent scatter and all- of the similarity between the behaviour of ESF sky meteor modes for observing ionosphere and turbulence and fluid turbulence, we will use the meteor, respectively. In the coherent scatter particle image velocimetry (PIV) technique to mode, the radar works like a Doppler coherent estimate the 2-D velocity field measurements of backscatter radar to detect ionospheric irreg- the imaging data. Among other procedures, we ularities in the E and F region of ionosphere. will use two interrogation images separated by While in meteor mode, the radar operates as an a known time that will be correlated to obtain all-sky interferometric specular meteor radar to the plasma displacement between two images. estimate neutral winds in a height range from 70 to 110 km. In this paper, a VHF radar TYPE: POSTER sounding method for simultaneously measur- DATE: 2012-03-15 – 17:30 ing ionospheric irregularities and upper atmospheric winds is presented. Some results of low- latitude ionospheric E and F region irregulari- P7.14 APPARENT ELECTRON DEN- ties from the VHF radar are also shown. More- SITY MODULATION UNDER RF HEAT- over, by tracking non-specular (coherent scat- ING AT EISCAT UHF AND ITS AP- ter mode) and specular (classical meteor mode) PLICATION FOR ESTIMATING THE meteor trail echoes as netural winds transport ELECTRON-ION TEMPERATURES RA- the plasma trails, the radar provides a good op- TIO portunity for high-resolution measurements of Henry Pinedo1, Cesar La Hoz1, Ove Havnes1, lower thermospheric winds. Since the radar can and Mike Rietveld2 nearly simultaneously get ionospheric irregularities and atmospheric winds in the same region, 1 University of Tromsø, Norway it will be very helpful to investigating the gener- 2 EISCAT Scientific Association, Norway ation mechanism of E region field-aligned irregularities (FAIs) due to the wind shear effects. In a co-located campaign with UHF radar and Heating EISCAT facilities on June 7 2010 TYPE: POSTER in Tromsø-Norway, standard EISCAT analysis DATE: 2012-03-15 – 17:30 show an apparent electron density modulation during heating-on times. The modulation is

111 ISEA13 - 13th International Symposium on Equatorial Aeronomy fairly evident at heights above 90 km of altitude obtained from a low-latitude location. The and is manifested as a depletion of density of measurements were carried out from Hyder- approximately 40% respect to the background abad, India, wherein three upper atmospheric level during heating-offtimes. The increase oxygen emission lines at 557.7 nm, 630.0 nm of electron temperature in a controlled way is and 777.4 nm that emanate from around 130 an expected result of artificial heating pertur- km, 230 km and 300 km, respectively have bation. However, the amount of energy re- been measured simultaneously using the multi- quired to produce density modulations sensible wavelength High resolution Echelle spectro- to radar systems on the ground is much more graph. Around 60 days of data obtained during than what the HF can produce and transfer January – April 2011 will be presented which to the plasma. The associated plasma trans- show different wave features at different emis- port process due to pressure gradients induced sions (different altitudes), different diurnal pat- by electron temperature variations is slowed terns that signify the wave dynamics at that al- down by the ion mass according to ambipo- titude, and latitudinal variations that reflect the lar diffusion. Therefore, the plasma transport effect of neutral- and electrodynamics of the time scale to produce measureable plasma de- low-latitude region. Such simultaneous mul- pletion is larger than the current 20sec Heating- tiple wavelength emission measurements pro- on time. The apparent electron density modu- vide us with a means of comprehensive inves- lation is attributable to how the corresponding tigations of vertical coupling in the upper at- parameters have been estimated. The assumed mosphere. Initial results on the variabilities of criterium of equal temperature for electrons these emissions will be presented. and ions inside the involved region is not valid under heating conditions. This situation pro- TYPE: POSTER vides an opportunity for simple and reliable esti- DATE: 2012-03-15 – 17:30 mation of Te/Ti ratio during heating-on times, based on a density modulation-less process using the radar equation. P7.17 EFFECTS OF VERTICAL VE- LOCITY SHEAR ON MEAN WIND TYPE: POSTER AND TURBULENCE KINETIC ENERGY DATE: 2012-03-15 – 17:30 ESTIMATES USING DOPPLER BEAM SWINGING AND SPACED ANTENNA TECHNIQUES P7.15 INVESTIGATIONS ON VER- TICAL COUPLING USING MULTI- Danny Scipion1, Robert Palmer2, Phillip WAVELENGTH DAYTIME OPTICAL Chilson2, and Evgeni Fedorovich2 EMISSIONS FROM LOW-LATITUDES 1 École Politechnique Fédérale de Lausanne, Duggirala Pallamraju1, Fazlul I. Laskar1, Switzerland Thatiparthi Vijaya Lakshmi2, and Supriya 2 University of Oklahoma, Norman, OK, USA Chakrabarti3 The two techniques most often used to re- 1 Physical Research Laboratory, Ahmedabad, trieve three-dimensional winds (zonal, merid- India ional, and vertical) from wind profiling radars 2 Jawaharlal Nehru Technological University, are Doppler Beam Swinging (DBS) and Spaced Hyderabad, India Antenna (SA). These well-known techniques 3 Boston University, MA, USA are based on the assumption of homogeneity across the region defined by the radar beam We present high-spectral resolution day- directions. However, this assumption is not al- time optical emission measurements at multiple ways valid due to the presence of spatial inho- wavelengths over a large (140o) field-of-view mogeneities in the wind field and shear. The

112 ISEA13 - 13th International Symposium on Equatorial Aeronomy present study employs a combination of a vir- between 0.5 - 3.0 around 90 km. However, at tual radar and Large-Eddy Simulations (LES) in higher altitudes around 98 km, this ratio in- order to evaluate different wind-profiling meth- creases to 10. 0. This work will present the ods of estimating wind in the presence of hor- annual distribution of neutral Ca over Arecibo izontal shear of vertical velocity. In the first and investigate the ion-neutral ratio during dif- stage, the ideal shear has been studied using ferent seasons. The study will illustrate the only the virtual simulator with constant param- relative contributions of chemistry and meteor eters for both techniques. Later, the shear ef- processes on the distribution of neutral Ca. fects of the vertical velocity sheer in the horizontal wind estimates are studied using the TYPE: POSTER virtual radar over a realistic case for the LES DATE: 2012-03-15 – 17:30 fields. Finally, it is observed that the horizontal shear of vertical velocity affects estimates of turbulence kinetic energy, which are obtained P7.19 DEVELOPMENT OF LOW-COST from wind estimates in both techniques. SKY-SCANNING FABRY-PEROT IN- TERFEROMETERS FOR AIRGLOW TYPE: POSTER AND AURORAL STUDIES DATE: 2012-03-15 – 17:30 Kazuo Shiokawa1, Yuichi Otsuka1, Shin-ichiro Oyama 1, Satonori Nozawa1, Mitsugi Sato1, P7.18 ANNUAL DISTRIBUTION OF Yasuo Kato1, Yoshiyuki Hamaguti 1, Mamoru NEUTRAL CALCIUM AND ITS DE- Yamamoto2, and John Meriwether3 PENDENCE ON ION VARIATION OB- TAINED USING RESONANCE LIDAR AT 1 ARECIBO Solar-Terrestrial Environment Laboratory, Nagoya University, Japan 2 Shikha Raizada1, Craig Tepley1, and Bifford Research Institute for Sustainable Hu- Williams2 manosphere, Kyoto University, Japan 3 Physics and Astronomy, Clemson University, 1 Arecibo Observatory, Puerto Rico Clemson, SC, USA 2 NorthWest Research Associates, Colorado Research Associates Division, Boulder, CO, We have developed four new-type Fabry- USA Perot interferometers (FPIs) that are designed to measure thermospheric winds and temper- Calcium, a non-volatile metal, displays dif- atures and also mesospheric winds through ferent characteristics than other volatile met- the airglow/aurora emissions at wavelengths of als like sodium. This is reflected in its defi- 557.7 nm and 630.0 nm. One FPI (FP01) pos- ciency compared to meteoric abundance. The sessing a large-aperture etalon (diameter: 116 vertically integrated densities of neutral Ca are mm) was installed at the EISCAT Tromsoe site about 100 - 150 times smaller when compared in 2009. The other three FPIs (FP02-FP04) with Na. The lack of neutral Ca in the meso- using 70-mm diameter etalons were installed sphere and the lower thermospheric region is in Thailand, Indonesia, and Australia in 2010- still controversial, with the role of meteor abla- 2011 with two pairs at geomagnetic conjugate tion and ion-neutral chemistry being the major sites. FP02-FP04 are low-cost compact in- factors governing the distribution of this metal. struments, suitable for multipoint network ob- One of the indicators of efficient chemistry is servations. All of these FPIs use low-noise the ion to neutral ratio, where high values sug- cooled-CCD detectors with 1024x1024 pixels gest slow conversion of the former to the lat- combined with a 4-stage thermoelectric cool- ter. Recent studies have pointed out that the ing system that can cool the CCD tempera- Ca+/Ca ratio is altitude dependent and ranges ture down to -80C. The large incident angle

113 ISEA13 - 13th International Symposium on Equatorial Aeronomy

(maximum: 1.3-1.4 degree) to the etalon in- second intelligent agent. Initial processing decreases the throughput of the FPIs. The air- tails and some simulation outcomes with based- glow and aurora observations at Tromsoe by intelligence that uses a support vector machine FP01 show wind velocities with typical random (SVM) classifier will be presented. The SVM errors ranging from 2 to 13 m/s and from 4 to technique is used for adaptation and optimiza- 27 m/s for mesosphere (557.7 nm) and thermo- tion of the real-time signals and data synop- sphere (630.0 nm) measurements, respectively. sis. The hardware needed to implement these The 630-nm airglow observations at Shigaraki, processes, which includes low-cost FPGAs in Japan, by FP02-FP04 give thermospheric wind addition to open source software tools, will velocities with typical random errors that vary also be described. Furthermore, using object- from 2 m/s to more than 50 m/s depending on oriented programming (OOP) techniques and airglow intensity. open-source tools, we illustrate a technique to provide a cost-effective, generalized software TYPE: POSTER framework to uniquely define an instrument’s DATE: 2012-03-15 – 17:30 functionality through a customizable interface. The new instrument is intended to provide instantaneous profiles of atmospheric parameters P7.20 TOWARDS THE IMPLEMENTA- and climatology on a daily basis throughout the TION OF A COGNITIVE RADAR TO year in Huancayo, near the Peruvian Andes. STUDY EQUATORIAL PLASMA INSTA- BILITIES TYPE: POSTER DATE: 2012-03-15 – 17:30 Robert Sorbello1, Julio Urbina2, and Zach Stephens1 P7.21 A GPU-BASED MONTE CARLO 1 Pennsylvania State University, State Park, ALGORITHM FOR THE SIMULATION PA, USA OF PARTICLE TRAJECTORIES IN H+, 2 Communications and Space Sciences Labora- HE+, AND O+ PLASMAS tory, Pennsylvania State University, University Daniel Angel Suárez Muñoz, Marco Milla, and Park, PA, USA Jorge Chau

A cognitive radar system is composed of Radio Observatorio de Jicamarca, Instituto Ge- three key components: 1) intelligent signal pro- ofísico del Perú, Lima, Perú cessing, which builds on radar interactions from the surrounding environment, 2) receiver feed- In order to study the effects of Coulomb col- back which is utilized by the transmitter to fa- lisions on incoherent scatter (IS) radar signals, cilitate an intelligent response to detected sig- Milla & Kudeki [2011] developed a Monte Carlo nals, and 3) preservation of radar echo informa- procedure to estimate the IS spectra for differ- tion contents. This paper describes initial steps ent sets of plasma parameters. This procedure in implementing a cognitive radar system for is based on the simulation of charged-particle studying various Equatorial phenomena occur- trajectories in ionospheric plasmas, a task that ring in the Earth’s ionosphere namely: Spread- requires high computational power. In this F, 150 km echoes, electrojet, and meteors. poster, we report on the development of a GPU These echoes are first categorized by signal pa- (Graphic Processing Unit) parallel computing rameters with known distributions, e.g., signal- algorithm that reduces the computational cost to-noise ratio, changes in range, instantaneous of particle-trajectory simulations. The algo- frequency, periodicity, etc. This information is rithm takes advantage of the multithreaded then parsed into an intelligent agent signal clas- processing capability of NVIDIA CUDA-enabled sifier that makes decisions from processed data GPUs, such that each thread simulates inde- and provides a synopsis of the results into a pendently the trajectory of a particle (either an

114 ISEA13 - 13th International Symposium on Equatorial Aeronomy electron or an ion) in a given plasma configura- GPS-TEC receivers installed at various airports tion but considering different initial conditions. under the GAGAN project, L-band scintillation The simulation results are time series of parti- was measured from GPS and GSAT-8 satellites cle velocities and displacements in three dimen- simultaneously. Scintillation measurements us- sions, results that are then used in the calcula- ing GPS are temporal and spatial in nature due tion of single-particle ACFs (Fourier transforms to orbital period of 11h 56 min. GSAT-8, being of the particle displacement distributions) and the geostationary satellite provides the unique the subsequent estimation of IS spectra. The opportunity to measure the scintillation at spe- description of our GPU algorithm to perform cific fixed location depending upon the receiver the simulations and compute the correlations location. It is well established that scintillation are presented together with statistics of our re- affects the user position accuracy and may lead sults. to loss of lock of the satellite. Such high scintillation at user receiver in the line of sight of Milla, M. A., and E. Kudeki (2011), Inco- GSAT-8 can potentially result into short ser- herent scatter spectral theories–Part II: Model- vice outage. We will be presenting, for the ing the spectrum for modes propagating per- first time, simultaneous observations of L-band pendicular to B, IEEE Transactions on Geo- scintillation from GPS and GSAT-8 over the science and Remote Sensing, 49(1), 329–345, Indian region. These results will highlight the doi:10.1109/TGRS.2010.2057253. occurrence pattern of scintillation to better understand the underlying phenomena. It will be TYPE: POSTER complimented by the morphological studies on DATE: 2012-03-15 – 17:30 L-band scintillation over the Indian equatorial sector using the GPS-TEC data of 2004-2011. P7.22 OBSERVATION OF SIMULTANE- OUS L-BAND SCINTILLATION FROM TYPE: POSTER GPS AND GSAT-8 DATE: 2012-03-15 – 17:30

Surendra Sunda1, P. V. Khekale1, K. S. Parikh1, A. S. Ganeshan2, and S.V.Satish3 P7.23 DEVELOPMENT OF A PASSIVE VHF RADAR SYSTEM USING SOFT- 1 Space Applications Centre, Ahmedabad, In- WARE DEFINED RADIO FOR EQUATO- dia RIAL PLASMA INSTABILITY STUDIES 2 ISRO Satellite Centre, Bangalore, India 3 Airports Authority of India, New Delhi, India Burak Tuysuz1, Julio Urbina2, and Frank Lind3 The geostationary satellite GSAT-8 carry- 1 ing the GAGAN (GPS Aided Geo Augmented Pennsylvania State University, State Park, Navigation) payload was successfully launched PA, USA 2 on May 21, 2011 and was positioned at 55o Communications and Space Sciences Labora- E. The L1 and L5 downlink frequencies are tory, Pennsylvania State University, University used to transmit the WAAS correction mes- Park, PA, USA 3 sages, whereas uplink of data is carried on C MIT Haystack Observatory, Massachusetts band. It is the first satellite from ISRO with Institute of Technology, MA, USA this kind of payload after the initial failure of GSAT-4. This has provided the fully func- In this paper we describe a bistatic pas- tional capability to the ambitious project of sive radar system named “Penn State University Indian Satellite Based Augmentation System- Passive Radar System (PSUPRS)” that uses GAGAN. GAGAN will provide the seamless nav- open source hardware and software defined ra- igation to civil aircrafts over the Indian flight in- dio resources to utilize non-cooperative FM ra- formation region. Using the ground network of dio transmitters for upper atmosphere remote

115 ISEA13 - 13th International Symposium on Equatorial Aeronomy sensing. The open source software defined ra- operating an incoherent scatter system to mea- dio toolkit GNU Radio is used to reduce sig- sure the state parameters of the ionosphere is nal processing needs and accompanied with the lost intermittently (in space and/or time) when open source hardware Universal Software Radio thermal equilibrium conditions are violated and Peripheral 2 (USRP2) for data acquisition. The the ionosphere becomes unstable and turbu- resultant system is highly flexible compared to lent. Since such “events” are quite routine near hardware based radio receivers and open to fu- the geomagnetic equator – e.g., equatorial elec- ture developments. We will offer the design trojet, 150 km irregularities, equatorial spread procedure and performance analysis of our in- F – there is much to be gained by maintaining strument with early results. We aim to place a continuous monitoring of the turbulent struc- PSUPRS near magnetic equator for a long term tures and studying their onset and evolution operation mainly because of the orientation of vis a vis ISR observations of ionospheric state the Earth magnetic field lines in the region. We parameters in time and space surrounding the also propose target locations near Lima, Peru turbulent structures and layers. The proposed for the planned bistatic operation to observe Huancayo station is in effect a “child” of Jica- ionospheric E and F region field aligned plasma marca in the sense that most of the techniques irregularities. to be used were first developed at Jicamarca – e.g., imaging radar interferometry, drift mea- TYPE: POSTER surements using 150 km echoes, etc. We will DATE: 2012-03-15 – 17:30 report current progress of the construction of the system and initial steps for its deployment.

P7.24 AN OVERVIEW OF A COGNITIVE TYPE: POSTER RADAR SYSTEM TO STUDY PLASMA DATE: 2012-03-15 – 17:30 IRREGULARITIES NEAR THE PERU- VIAN ANDES P7.26 RADIO OCCULTATION METH- Julio Urbina ODS FOR MONITORING ATMO- SPHERE AND IONOSPHERE OF THE Communications and Space Sciences Labora- EARTH tory, Pennsylvania State University, University Park, PA, USA Victor Hugo Rios, Sebastian Leal, and Hernan Esquivel We describe the implementation of a VHF coherent imaging radar in Huancayo, near the Universidad Nacional de Tucuman, Argentina Peruvian Andes to initiate continuous monitoring of the plasma structuring in the equatorial The remote sensing satellite radio occul- ionosphere. The new radar system will utilize tation method elaborated for monitoring of cognitive sensing techniques and complement the earth’s atmosphere and ionosphere with the ionospheric observations conducted by the a global coverage is described. Comparison Jicamarca incoherent scatter radar (ISR), lo- of theoretical results with experimental obser- cated about 170 km to the west of Huancayo vations of radio wave propagation eﬀects in along the geomagnetic equator. The main pur- the earth’s atmosphere and ionosphere in the pose of the new system will be to obtain unin- communication links satellite-to-satellite is pro- terrupted images of ionospheric structuring and vided. Directions in application of the ra- drifts from Huancayo, which are only probed dio occultation method are discussed: mea- and sampled intermittently from Jicamarca due suring vertical gradients of the refractivity in to the operation costs and scheduling issues of the atmosphere and electron density in the the more powerful incoherent scatter system. lower ionosphere, determination of the tem- It should be noted that the main advantage of perature regime in the stratosphere and tropo-

116 ISEA13 - 13th International Symposium on Equatorial Aeronomy sphere, investigation of the internal wave activ- that raw product from an experiment is rela- ity in the atmosphere, and study of the iono- tive TEC along the slant ray-path from a satel- spheric disturbances on a global scale. The ra- lite to the GRBR. Estimation of offset for each dio occultation technique may be applied for in- satellite pass is essential to obtain the abso- vestigating the relationships between processes lute TEC. Well known technique for it is the in the atmosphere and mesosphere, study of two station method proposed by Leitinger et thermal regimes in the intermediate heights al. [1975]. In the study of day-to-day variability of the upper stratosphere-lower mesosphere, of the low-latitude/equatorial ionosphere, how- and for analysis of influence of space weather ever, the GRBR network is too sparse to apply phenomena on the lower ionosphere. Radio- this method in many situations. In our study of holographic methods are considered as a tool large-scale wave structure (LSWS), we use the for determination of the altitude profiles of tem- beacon signal from C/NOFS satellite, and es- perature, pressure, refractivity, internal wave timate the offset by assuming linearly trended activity in the atmosphere, and electron den- TEC distribution with longitude. S. Tulasi Ram sity in the ionosphere with usage of the radio et al. [2011] recently showed that this “one- links satellite-to-satellite. Results of radio oc- station” approach can be very effective to to cultation measurements of the atmospheric and our study purpose. Now we try to use data ionospheric parameters are described. Compar- from other polar-orbiting satellite at a single ative analysis of effectiveness of the radio oc- station, or with the very sparse receiver net- cultation and other remote sensing methods is work. In this presentation we discuss problems conducted. and solutions to estimate offset of observations, and obtain the absolute TEC. TYPE: POSTER DATE: 2012-03-15 – 17:30 TYPE: POSTER DATE: 2012-03-15 – 17:30

P7.28 ESTIMATION OF ABSOLUTE TEC WITH GNU RADIO BEACON RE- P7.31 COMPARISON OF EQUATORIAL CEIVER (GRBR) TEC AT AFRICAN AND AMERICAN LONGITUDES DURING THE MINIMUM AND ASCENDING PHASES OF SOLAR Mamoru Yamamoto1, Kensuke Hangyo1, S. CYCLE 24 Tulasi Ram2, and Roland Tsunoda3 Andrew Akala1, Patricia Doherty2, Cesar 1 Research Institute for Sustainable Hu- Valladares2, Charles Carrano2, Endawoke manosphere, Kyoto University, Japan Yizengaw2, Gopi Seemala3, and Juan Carlos 2 Equatorial Geophysical Research Laboratory, Espinoza4 Indian Institute of Geomagnetism, India 3 SRI International, Menlo Park, CA, USA 1 University of Lagos, Nigeria 2 Boston College, MA, USA GNU Radio Beacon Receiver (GRBR) is a 3 K.L. University, India simple digital receiver for satellite-ground bea- 4 Radio Observatorio de Jicamarca, Instituto con experiment to measure ionospheric total Geofísico del Perú, Lima, Perú electron content (TEC). This is a unique instrument that is based on the open-source hardware This study compares equatorial total elec- “Universal Software Radio Peripheral (USRP)” tron content (TEC) at African and Ameri- and the open-source software “GNU Radio”. can longitudes during the minimum (2009) TEC is measured from phase diﬀerences be- and ascending (2011) phases of solar cycle tween dual-band beacon signals at 150 and 24. GPS-TEC data, which were observed at 400MHz. One problem of this experiment is the same local time at two equatorial stations

117 ISEA13 - 13th International Symposium on Equatorial Aeronomy on both longitudes: Lagos (6.52oN, 3.4oE, solar minimum of cycle 23/24. GPS observa- 3.04oS magnetic latitude) [NIGERIA] and Pu- tions provide information about values of ver- callpa (8.38oS, 74.57oW, 4.25oS magnetic lat- tical total electron content (TEC) up to the itude) [PERU] were used for the investigation. 20,200 km. FormoSat-3/COSMIC now pro- These data were grouped into daily, seasonal vides unprecedented global coverage of GPS and solar activity sets. Receiver and satel- RO measurements. Depending on the state of lites biases were obtained from the Data Cen- the constellation, COSMIC has been producing tre of the Bern University, Switzerland, and 1,500 – 2,500 good soundings of the ionosphere they have been carefully removed from the TEC and atmosphere per day, uniformly distributed data. Furthermore, in order to eliminate mul- around the globe. This number of RO is much tipath effects from the data, elevation angle higher than even before. In this study, COSMIC cut-offof 30o was adopted. The hourly av- RO data for different seasons corresponded to erages of each data set were determined. In equinoxes and solstices of 2009 (March, June, conclusion, the day-to-day variation in verti- September and December) were analyzed. All cal TEC (VTEC) recorded the maximum dur- selected COSMIC RO electron density profiles ing 1400–1600 LT hours and minimum dur- were integrated up to the height of 700 km (al- ing 0400–0600 LT hours at both longitudes. titude of COSMIC satellites), in that way the Seasonally, maximum VTEC values were ob- estimates of ionospheric electron content (IEC) served during Equinoxes and minimum during were retrieved on a global scale. The final IGS Solstices. VTEC also increased with solar ac- combined global ionospheric maps (GIMs) were tivity. On longitude by longitude comparison, used to calculate the global maps of monthly the African sector recorded the highest VTEC medians of TEC values. As a result there were values than the American sector. Overall, this analyzed global distributions of GPS TEC and study re-affirms the uniqueness of the dynam- IEC estimates corresponded to the monthly me- ics of the African equatorial ionosphere, and dian values for different seasons of 2009. We the need for further research efforts that could consider the quantitative differences PEC = support better understanding of these dynam- TEC – IEC as a measure of the contribution ics. of the PEC to GPS TEC. In order to analyze seasonal behaviour of PEC contribution to GPS TYPE: POSTER TEC at the different regions we selected several DATE: 2012-03-15 – 17:30 specific points with coordinates, corresponded to the approximate positions of different, midlatitude and low-latitude, ionospheric sounding P7.32 INVESTIGATION OF THE PLAS- stations. Such points were selected at Northern MASPHERE CONTRIBUTION TO THE America, European and Asian regions, South- GPS TEC UNDER SOLAR MINIMUM ern America, Southern Africa and Australia. CONDITIONS For each specific points GPS TEC, COSMIC IEC and PEC estimates were analyzed. Results Irina Zakharenkova1, Iurii Cherniak1, Andrzej of our comparative study revealed that for mid- Krankowski2, and Irk Shagimuratov1 latitude stations PEC estimates varied weakly with the time of a day and reached the value 1 West Department of IZMIRAN, Kaliningrad, of several TECU (3-5 TECU) for the condition Russia of solar minimum. Percentage contribution of 2 Institute of Geodesy, University of Warmia PEC to GPS TEC indicates the clear depen- and Mazury, Olsztyn, Poland dence from the time and varies from a minimum of about 25-30% during day-time to the The plasmaspheric electron content (PEC) value of more than 60% at night-time. was estimated by comparison GPS observations and FORMOSAT-3/COSMIC radio oc- TYPE: POSTER cultation (RO) measurements at the extended DATE: 2012-03-15 – 17:30

118 ISEA13 - 13th International Symposium on Equatorial Aeronomy

This distributed observatory is mainly consti- tuted by three types of instruments: GPS re- P7.33 LISN OBSERVATORY: DATA ceivers, ionosondes and magnetometers, instru- PRODUCTS AND RESULTS ments that are continuously collecting data and send a heavy volume of information to a cen- César De La Jara1, Juan Carlos Espinoza1, tral server located at the Instituto Geofísico del César Valladares2, and Jorge Chau1 Perú (IGP). In order to facilitate the access to the database for the LISN users, a collection 1 Radio Observatorio de Jicamarca, Instituto of programs and web-oriented interfaces have Geofísico del Perú, Lima, Perú been developed to carry out diﬀerent tasks such 2 Boston College, MA, USA as management, analysis, processing, and visu- alization of the measured data and estimated The Low-Latitude Ionospheric Sensor Net- parameters. In this poster, a summary of the work (LISN) monitors the low, middle and high data products measured with the LISN server atmosphere in the equatorial region with the is presented. In addition, the tools developed purpose of studying and forecasting ionospheric for the data analysis will be described. phenomena. LISN is composed of an array of modern geophysical instruments deployed in TYPE: POSTER South America, near the position reference of DATE: 2012-03-15 – 17:30 the magnetic equator and the meridian 70oW.

119 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Session 8

FUTURE TRENDS AND CHALLENGES

• Altitude and latitude coupling as drivers for equatorial dynamics (stratospheric warming eﬀects, migrating vs. non-migrating tides, F region/E region coupling eﬀects in the equatorial region and for midlatitude irregularities).

• Extracting new information from existing techniques (e.g., radar imaging, meteor trail tracking, dynamical parameters from network measurements).

• Integrating large datasets (multiple instrument datasets, model output/dataset integration).

• Next-generation numerical models of the coupled geospace system.

• Meeting the operational needs for space weather prediction.

Conveners: M. Larsen, M. Hagan, and C. La Hoz

120 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - STUDY OF SOLAR FORC- Anthea Coster1, Endawoke Yizengaw2, and ING AND ATMOSPHERIC COUPLING Mark Moldwin3 EFFECTS TO THE IONOSPHERE BY USING FORMOSAT-3/COSMIC 1 MIT Haystack Observatory, Massachusetts AND FORTHCOMING FORMOSAT- Institute of Technology, MA, USA 7/COSMIC-II MISSION 2 Boston College, MA, USA 3 Department of Atmospheric, Oceanic and Chao-Han Liu1, Jann-Yenq Liu2, and Charles Space Sciences, University of Michigan, MI, Lin3 USA

1 Academia Sinica, Taiwan The distribution of equatorial ionospheric 2 National Space Organization, Taiwan plasma is strongly influenced by multiple com- 3 National Cheng Kung University, Taiwan peting factors, including solar heating, tidal forces, equatorial electrodynamics, and the hor- The ionospheric electron density structures izontal magnetic field geometry. Much of our are modulated by forcing from the solar out- understanding of this complex ionospheric re- puts and upward propagating tides/planetary gion has been gained from observations made waves of lower atmosphere origins. The mod- with the incoherent scatter radar at Jicamarca ulated global ionospheric effects, including ef- in the American sector. However, in the Amer- fects from the periodic solar wind, magnetic ican sector, there is a fairly large excursion, storm, troposphere excited tides and strato- or dip, between the geomagnetic and geode- spheric sudden warming, are revealed by con- tic equators, a factor that adds to the com- tinuous observations of electron density pro- plexity of the physics. In the African sec- files derived retrieved from GPS radio occul- tor, where there is currently no incoherent (or tation soundings of FORMOSAT-3/COSMIC coherent) scatter radar, the geomagnetic and during 2006-2011. These results prove that geodetic equators are reasonably parallel, sep- the continuously available three-dimensional arated by at most 10 degrees. To further add global observation of the ionospheric elec- to this already complex picture, the South At- tron density is crucial for better understand- lantic Anomaly, a region where the magnetic ing the dynamics of Earth’s upper atmo- field is ‘weaker’, lies in between the American sphere. As the result, a continuous satel- and African sectors. lite constellation capable of performing more GNSS radio occultation soundings is planned Data from satellites (e.g. ROCSAT, and named as FORMOSAT-7/COSMIC-II. In C/NOFS, DMSP) have indicated that the this study, we first review scientific achieve- equatorial ionosphere in the African sector re- ments of solar wind, ionosphere, and atmo- sponds differently than other sectors. For ex- sphere coupling studies by using FORMOSAT- ample, ionospheric bubbles have been observed 3/COSMIC observations. Following the brief to be much deeper and to occur more fre- review, the planned FORMOSAT-7/COSMIC- quently in the African sector. It has also been II mission and its potential application in fur- reported that ionospheric depletions more fre- ther exploring the coupling ion effects are in- quently rise to higher altitudes (up to 1000+ troduced. km) in the African sector than those in other longitude sectors. To date, these observations TYPE: ORAL have not been confirmed, validated or studied DATE: 2012-03-16 – 10:30 in detail by observations from the ground due to lack of suitable ground-based instrumentation in Africa. The causes or driving mechanisms of INVITED - RADAR INSTRUMENTA- the unique density irregularities, bubbles, and TION IN THE AFRICAN SECTOR: WHY depletions in the African sector remain unre- AND HOW solved.

121 ISEA13 - 13th International Symposium on Equatorial Aeronomy

To address these issues, the U.S. National backscatter returns), (2) the large JRO array Science Foundation has recently sponsored a (for winds), (3) standard meteorological bal- workshop at Boston College to consider the loon releases from Lima and (4) a miniature possibility of relocating an Advanced Modular autonomous vehicle (MAV) that was carried Incoherent Scatter Radar (AMISR) to Ethiopia. to altitude by a conventional meteorological The primary purpose of this workshop was to balloon. The MAV (‘DataHawk’) was then deﬁne the science goals motivating such a move released to record temperature measurements and to examine the technical and logistical is- during descent. The DataHawk was designed sues involved. This talk will summarize the and instrumented at the University of Colorado ﬁndings of this workshop. in Boulder, and can provide all of the in situ data mentioned above to altitudes of at least TYPE: ORAL 10 km in future experiments. DATE: 2012-03-16 – 10:55 TYPE: ORAL DATE: 2012-03-16 – 11:20 INVITED - A PRELIMINARY LOOK AT VERTICALLY THIN TROPOSPHERIC RADAR ECHOES BOTH RADAR AND INVITED - APERTURE SYNTHESIS SITU MEASUREMENTS RADAR IMAGING FOR UPPER ATMO- SPHERIC RESEARCH Ben Balsley1, Dale Lawrence2, Ron Woodman3, and Dave Fritts4 David Hysell1 and Jorge Chau2

1 CIRES, University of Colorado Boulder, CO, 1 Cornell University, Ithaca, NY, USA USA 2 Radio Observatorio de Jicamarca, Instituto 2 Aerospace Engineering Sciences, University of Geofísico del Perú, Lima, Perú Colorado Boulder, CO, USA 3 Instituto Geofísico del Perú, Lima, Perú Aperture syntheis imaging offers a means 4 NorthWest Research Associates, Colorado of observing upper atmospheric phenomena Research Associates Division, Boulder, CO, in three spatial dimensions with fixed-beam USA radars. The data supporting the imagery are cross-spectral visibility estimates obtained from We report results of an initial campaign de- spaced receivers on the ground. Extracting signed to provide high-resolution in situ tem- imagery from the data is an inverse problem perature profiles in conjunction with concurrent and prompts an investigation of the existence, VHF radar measurements through the same uniqueness, and stability of the solution. We tropospheric volume. The immediate focus is describe an approach to the imaging problem on clarifying the background atmospheric prop- based on the MaxEnt algorithm, a Bayesian in- erties in the vicinity of vertically narrow regions version scheme that uses Shannon’s entropy as of enhanced radar backscatter previously re- a prior probability estimate. We discuss error ported by Woodman et al. (20xx). Future fo- propagation along with a few extensions to the cus will be on incorporating such temperature basic algorithm useful for upper-atmospheric profiles, along with additional high-resolution in applications. Finally, we demonstrate the algo- situ data on winds, humidity, and turbulence, rithm in the context of ionospheric plasma den- into DNS models in order to establish the per- sity irregularities using coherent scatter data tinent dynamical processes underlying the en- from the Jicamarca Radio Observatory. hanced echo-producing mechanisms. TYPE: ORAL The present talk includes concurrent data DATE: 2012-03-16 – 11:45 from (1) the SOUSY Radar (for high-resolution

122 ISEA13 - 13th International Symposium on Equatorial Aeronomy

INVITED - COUPLING BETWEEN THE Huixin Liu1, Mamoru Yamamoto2, Y. LOWER AND UPPER ATMOSPHERE Yamazaki1, and K. Yumoto1 DURING STRATOSPHERIC SUDDEN 1 WARMINGS: TRENDS AND CHAL- Kyushu University, Japan 2 LENGES Research Institute for Sustainable Hu- manosphere, Kyoto University, Japan Larisa Goncharenko1 and Jorge Chau2 Stratosphere sudden warming (SSW) is a 1 Haystack Observatory, Massachusetts Insti- local meteorological event with a global impact. tute of Technology, Westford, Massachusetts, Strong semi-diurnal perturbation in the vertical USA plasma drift and TEC has been frequently re- 2 Radio Observatorio de Jicamarca, Instituto ported. A general depletion of the plasma and Geofísico del Perú, Lima, Perú thermospheric density has also been observed during the 2009 major SSW, indicating a sub- Sudden stratospheric warming events have stantial cooling in the upper atmosphere. Now recently received significant attention as a we ask, are these features common to all SSW? prime example of strong coupling between the What are the differences between responses to lower and upper atmosphere, in particular at major and minor SSW? Using ground and satel- equatorial and tropical latitudes. New results lite observations, ionospheric electrodynamics, on drastic changes in the plasma density during thermosphere variation and the global Sq cur- SSW events have stimulated numerous studies rent are investigated in Asian, Africa and Peru- of possible connections between the lower and vian sectors to elucidate the above questions. upper atmosphere and have raised many questions about the mechanisms of these connec- TYPE: ORAL tions. They also highlighted major challenges DATE: 2012-03-16 – 12:35 for both observational and modeling communi- ties. For observational community, there is a INVITED - POLAR AND EQUATORIAL critical need for obtaining global-scale meso- MESOSPHERIC ENHANCED RADAR spheric and ionospheric data sets with high ECHOES REVISITED temporal and spatial resolution that is necessary to extract tidal signatures in various pa- Cesar La Hoz rameters and examine roles of various tides (solar and lunar, migrating and non-migrating, di- University of Tromsø, Norway urnal, semidiurnal, and terdiurnal). For understanding the vertical and latitudinal coupling, Enhanced radar echoes from the meso- atmosphere-ionosphere global coupled models sphere, regardless of geographic location, are need to treat seamlessly the neutral atmo- caused by neutral air turbulence that drives sphere from the troposphere to the thermo- the electron density fluctuations that ultimately sphere, as to include self-consistently electro- produce the radar wave scattering. The key dynamics. We will discuss these challenges and question is under what conditions the spatial outline several outstanding questions that are spectrum of the electron fluctuations has com- particularly interesting for further research. ponents (at the radar’s Bragg scale) of the appropriate strength to produce the observed TYPE: ORAL signal intensity. The simpler case is when the DATE: 2012-03-16 – 12:10 neutrals couple directly to the electrons at the Bragg scale. This is the case in the lower mesosphere (below about 80 km) where the Kol- INVITED - UPPER ATMOSPHERE RE- mogorov scale length can be of the order of, or SPONSE TO MAJOR AND MINOR smaller than, the relevant Bragg scale (typically STRATOSPHERE SUDDEN WARMING around or less than 3 metres for VHF radars).

123 ISEA13 - 13th International Symposium on Equatorial Aeronomy

This situation requires either, enhanced elec- due to ambipolar coupling, thus prolonging the tron densities (possible at high latitudes via inertial subrange beyond the Kolmogorov scale energetic auroral precipitation), or a powerful and covering the Bragg scale of typical VHF radar (such as the 50 MHz Jicamarca radar). radars. The enhanced echoes are known as The former case may apply to Polar Meso- Polar Mesospheric Summer Echoes (PMSE). A spheric Winter Echoes (PMWE), and the lat- few issues still remain, such as the role of meter case to measurements obtained with the teoritic smoke in both, the polar winter echoes Jicamarca radar near the equator. The more and the equatorial echoes, as the overshoot involved case is when the electron fluctuation effect (under artificial RF heating) has been spectrum requires an additional agent to ex- observed in polar winter echoes. We present tend its inertial subrange beyond the neutral’s an alternative calculation of the cross section Kolmogorov scale. This occurs in the upper of the equatorial echoes and compare the re- mesosphere (80 km and above) where the Kol- sults with the cross section of the polar winter mogorov scale can be several tens of metres for echoes under the assumption that the electron typical energy dissipation rates. The agent are fluctuations have a Kolmogorov spectrum. charged ice particles that occur only at high latitudes during summer. The electrons acquire TYPE: ORAL the diffusion rate of the massive ice particles DATE: 2012-03-16 – 13:00

124 ISEA13 - 13th International Symposium on Equatorial Aeronomy

AUTHOR INDEX

A Burrell, A., 59 Abad, R., 107 Abadi, P., 21 C Abalde, J., 42, 47, 102 Candido, C., 78 Abdu, M., 38, 61, 70, 78, 84, 95 Carrano, C., 117 Akala, A., 117 Carrasco, A., 79 Akinlade, G., 20 Castilho, C., 103 Akmaev, R., 39, 65, 68, 70 Castillo, O., 103 Alexander, J., 36 Caton, R., 106 Alves, E., 44 Chakrabarti, S., 67, 112 Ambili, K., 52, 63, 88 Chakrabarty, D., 86 Anad, F., 90 Chakraborty, S., 24 Anderson, D., 59, 70, 101 Chandra, H., 22 Andrioli, V., 42 Chang, G., 18 Aponte, N., 73 Chang, L., 40, 45 Aquino, M., 38 Chapagain, N., 65 Aveiro, H., 10, 16 Chatterjee, S., 24 Ayoola, M., 20 Chau, J., 17, 26, 45, 57, 59, 98, 103–105, 107– 109, 111, 114, 119, 122, 123 B Chen, C., 38 Bageston, J., 42, 47 Chen, S., 18, 95, 102 Bagiya, M., 18, 24 Chen, Y., 60 Bailey, G., 70, 95 Cherniak, I., 32, 85, 90, 118 Balsley, B., 122 Chernigovskaya, M., 43 Banola, S., 22 Chilson, P., 112 Batista, I., 38, 61, 70, 78, 79, 84, 110 Choosakul, N., 38 Batista, P., 38, 42, 44, 45, 47, 48, 50 Choudhary, R., 52, 63, 88 Baumgardner, J., 68, 108 Chu, Y., 29 Bernhardt, P., 98, 107 Clemesha, B., 42, 44, 45, 48, 50 Bertoni, F., 61, 96 Clemmons, J., 55, 72 Bessarab, F., 43 Codrescu, M., 70 Bhaskara Rao, S., 77 Condor, P., 43, 48, 108 Bhattacharyya, A., 12, 22, 28, 33, 47 Condori, L., 107, 108 Borges, W., 102 Correia, E., 95, 102 Bristow, W., 26 Cosgrove, R., 32 Bruinsma, S., 40 Costa, J., 86 Brum, C., 49 Costa, R., 67 Brunini, C., 108 Coster, A., 45, 57, 59, 121 Bubenik, D., 99 Criddle, N., 66 Bullet, T., 55, 108 Crowley, G., 54, 70, 103 Buriti, R., 37, 44, 48, 50, 65, 75 Cueva, R., 27 Burke, W., 98 Cunha-Neto, A., 103

125 ISEA13 - 13th International Symposium on Equatorial Aeronomy

D Frey, H., 54 Damtie, B., 90, 101 Fritts, D., 36, 42, 122 Dao, E., 10 Fukushima, D., 56 De Abreu, A., 43, 87 Fuller-Rowell, T., 39, 65, 68–70, 94 De Campos Velho, H., 95 De Jesus, R., 43, 87 G De La Beaujardiere, O., 98, 107 Galindo, F., 15, 108 De La Jara, C., 119 Ganesh, P., 67 De Meneses, F., 23, 75 Ganeshan, A., 115 De Nardin, C., 27, 78, 86, 95, 102 Gao, B., 15 De Paula, E., 27, 64, 86, 110 Garcia, J., 93 De Soria-Santacruz Pich, M., 73 Gardner, C., 37 Delay, S., 54 Gargarela, W., 103 Doherty, P., 117 Garner, T., 98 Dolman, B., 36 Gatto, R., 86 Domingos, S., 102 Gentile, L., 98 Dyrud, L., 15, 16, 108 Gerard, J., 54 Gerrard, A., 75, 104 E Ghodpage, R., 22 Earle, G., 107 Gobbi, D., 37 Eccles, V., 69, 70 Godefroy, M., 91, 109 Edelstein, J., 54 Goi, Y., 38 Egito, F., 50 Goncharenko, L., 43, 45, 49, 57, 59, 123 Emery, B., 59 Gonzalez, S., 49, 72, 73 Emmert, J., 59 Greenwald, R., 26 Emperumal, K., 33, 64 Groves, K., 83 England, S., 54 Guevara, W., 49, 89, 92, 94 Englert, C., 54 Guizelli, L., 27, 78, 95, 102 Erickson, P., 85 Gularte, E., 108 Escate, R., 92 Gurubaran, S., 18, 64 Espinoza, J., 117, 119 Esquivel, H., 116 H Euribe, C., 89 Hagan, M., 41 Hajra, R., 24 F Hamaguti, Y., 113 Fagundes, P., 42, 43, 47, 87, 102 Hamza, A., 13 Fang, T., 39, 68–70 Hangyo, K., 10, 117 Farley, D., 26 Haralambous, H., 74, 92 Fedorovich, E., 112 Harding, B., 65 Fedrizzi, M., 59 Harlander, J., 54 Fejer, B., 59 Hasbi, A., 23 Fentzke, J., 15, 16, 49, 72 Havnes, O., 111 Ferradas, C., 49, 89 Hecht, J., 66 Filho, A., 103 Heelis, R., 54, 59, 98, 107 Filippov, S., 19 Hei, M., 53, 98 Fisher, D., 65, 75 Hickey, D., 76 Forbes, J., 40, 54 Hossain, M., 44, 56 Foster, J., 84, 85 Hsieh, S., 35 Franke, S., 55, 66 Hsu, V., 49 Freudenreich, H., 11, 55, 71 Hu, K., 73

126 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Hu, L., 111 Lefteris, E., 74 Hu, R., 73 Leschenko, V., 32 Huang, C., 54, 98 Li, G., 20, 111 Huang, Y., 65 Liebrecht, C., 11 Huba, J., 52, 54, 70, 83 Lima, R., 103 Hubert, B., 54 Lin, C., 18, 40, 45, 121 Hunton, D., 107 Lin, J., 40, 45 Hysell, D., 10, 16, 17, 52, 54, 55, 122 Lind, F., 115 Liu, A., 66 I Liu, C., 121 Ilma, R., 16 Liu, G., 91 Immel, T., 54, 91 Liu, H., 35, 43, 48, 123 Iyemori, T., 38 Liu, J., 121 J Liu, L., 39, 42, 60 Janches, D., 108 Liu, T., 18 Jeeva, K., 22 Lühr, H., 12, 62, 100 Joyce, G., 70, 83 M K MacKinnon, A., 36 Kakad, B., 12, 22, 28, 33 Macotela, E., 49, 89, 94 Kamalabadi, F., 54 Madhav Haridas, M., 93 Karpachev, A., 48, 69 Makela, J., 32, 54, 65, 75 Karpov, I., 43 Makita, K., 95 Kato, Y., 113 Malakar, N., 98 Kelley, M., 10, 13 Malhotra, A., 15 Khekale, P., 115 Mangognia, T., 37 Kherani, E., 23, 27, 64 Manju, G., 93 Kil, H., 32 Martinez-Sanchez, M., 73 Klenzing, J., 11, 55, 71 Martinis, C., 68, 76, 108 Klimenko, M., 23, 43, 48, 69, 73, 87 Maruyama, N., 69, 94 Klimenko, V., 23, 43, 48, 69, 73, 87 Mathews, J., 15, 105 Korenkov, J., 32, 43 Matsumura, M., 38 Kovalam, S., 36 Maurya, R., 22 Krall, J., 83 Maute, A., 41, 54, 69, 70, 94 Krankowski, A., 118 Mayer, L., 69 Kubota, M., 56 Mazumdar, S., 24 Kudeki, E., 17, 55, 104, 109 Medeiros, A., 37, 44, 65 Kuyeng, K., 26, 107, 108 Mende, S., 54 Mendillo, M., 68, 108 L Meriwether, J., 65, 75, 104, 113 La Hoz, C., 111, 123 Mesquita, F., 103 Lago, A., 86 Milla, M., 17, 104, 105, 108, 109, 114 Lakshmi, T., 112 Miller, E., 26, 32 Larsen, M., 55 Millward, G., 70 Lary, D., 98 Miranda, O., 86 Laskar, F., 67, 112 Mirez, J., 93 Lawrence, D., 122 Mitchell, C., 110 Le, H., 60 Miyoshi, Y., 50 Leal, S., 116 Mlynczak, M., 46 Lee, M., 73 Moldwin, M., 90, 101, 121

127 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Monteiro, A., 42 Photos, V., 74 Moro, J., 27, 78, 95, 102 Pinedo, H., 26, 111 Mota Lima, L., 38, 44, 45 Pradipta, R., 73 Muella, M., 42, 110 Pugmire, J., 66 Muralikrishna, P., 14, 23, 75 Pulinets, S., 73 Muslim, B., 21 R N Raizada, S., 113 Nagatsuma, T., 56 Ratovsky, K., 43, 48 Nair, K., 22 Raulin, J., 49, 61, 89, 92, 94, 96, 103 Nakagawa, S., 31 Reid, I., 36 Narayanan, V., 18, 64 Reinisch, B., 62 Navarro, L., 65, 75, 105 Ren, Z., 39 Nayak, C., 22, 33 Rengifo, J., 92 Negrea, C., 69 Resende, L., 27, 78, 95, 102 Nguyen, T., 20 Retterer, J., 70, 98 Ning, B., 20, 42, 111 Reyes, P., 104 Nishioka, M., 31, 38, 56 Reynolds, A., 103 Nogueira, P., 70, 78, 84 Richards, P., 69 Nossa, E., 55 Richmond, A., 41, 69, 70, 94 Nozawa, S., 113 Ridley, A., 70 Rietveld, M., 111 O Rios, V., 116 Oliver, W., 76 Ritter, P., 62 Olsen, N., 100 Roble, R., 41, 43 Onohara, A., 38 Rochus, P., 54 Otsuka, Y., 31, 38, 53, 56, 102, 113 Roddy, P., 54, 98, 102 Oyama, S., 113 Rodrigues De Araújo, L., 45 Oyekola, O., 63, 76 Rodrigues De Souza, J., 62, 70, 86, 95 Rodrigues, F., 64, 103 P Rodriguez, P., 105 Pacheco, E., 61 Rooker, L., 73 Padilha, A., 86, 102 Rother, M., 100 Paes, R., 110 Rowland, D., 11, 55, 71 Pallamraju, D., 67, 92, 112 Ruohoniemi, J., 26 Palmer, R., 112 Russell, J., 46 Pant, T., 40, 44, 56, 89 Parikh, K., 115 S Park, J., 12, 62 Sahai, Y., 43, 87 Patil, P., 22, 64 Saito, A., 38 Patra, A., 22, 28, 77 Saito, S., 38 Paulino, A., 48 Sant Anna, N., 86 Paulino, I., 37 Santos, A., 78, 84 Pautet, P., 66 São Sabbas, F., 106 Paxton, L., 32, 35, 46 Satish, S., 115 Peddapati, P., 77 Sato, M., 113 Pereira, A., 95 Sazykin, S., 94 Petry, A., 95 Scherliess, L., 59, 70 Pfaﬀ, R., 11, 54, 55, 71, 79, 90, 98, 101, 102, Schuch, N., 48, 95, 102 107 Scipion, D., 112

128 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Seemala, G., 117 Tulasi Ram, S., 10, 28, 117 Sekar, R., 14 Tuysuz, B., 115 Selvaraj, C., 22 Seran, E., 91, 109 U Seyler, C., 10 Urbina, J., 15, 16, 55, 108, 114–116 Shagimuratov, I., 85, 118 Urco, M., 17, 108, 111 Sheehan, R., 53 Uyar, A., 73 Shepherd, S., 26 V Shi, J., 21 Vadas, S., 37 Shim, J., 59 Valladares, C., 26, 53, 98, 100, 101, 117, 119 Shiokawa, K., 31, 53, 56, 113 Vargas, F., 37, 42, 48 Shume, E., 64, 70 Varney, R., 52 Siefring, C., 98 Vasyliunas, V., 87 Simões, F., 79 Veliz, O., 65, 75 Skinner, W., 46 Vesnin, A., 43, 48 Smith, D., 35 Vidal Safor, E., 104 Sobral, J., 37, 61, 62, 78, 84 Vierinen, J., 105 Sojka, J., 70 Vincent, R., 36 Sorbello, R., 114 Vineeth, C., 40, 44 Sridharan, R., 18, 24, 88 Vogel Ely, C., 79 Sripathi, S., 12, 22, 28, 33, 47, 80 Sroten, J., 61 W Stephan, A., 54 Walterscheid, R., 72 Stephens, Z., 114 Wan, W., 39, 42, 60 St-Maurice, J., 52, 63, 88 Wang, H., 39, 68 Stolle, C., 62, 100 Westerhoﬀ, J., 37 Stoneback, R., 54, 59, 98 Whitehurst, L., 73 Strauss, P., 107 Wilder, R., 103 Su, Y., 98 Wilkens, M., 98 Suárez Muñoz, D., 114 Wilkinson, P., 53 Sulzer, M., 72, 73 Williams, B., 113 Sumod, S., 44, 56, 89 Woodman, R., 122 Sunda, S., 18, 115 Wrasse, C., 37, 38 Surve, G., 22 Wright, A., 76 Sutton, E., 54 Wroten, J., 68 Swartz, W., 26 Wu, F., 39, 65, 68 Swenson, G., 37, 48, 54, 66 Wu, Q., 59

T X Takahashi, H., 37, 38, 50, 86 Xiong, C., 62 Talaat, E., 26, 32, 35, 46 Xiong, J., 39, 42 Taramona, J., 93 Xu, J., 23 Taylor, M., 66 Tepley, C., 73, 113 Y Thampi, S., 99 Yamamoto, M., 10, 20, 99, 102, 113, 117, 123 Tisnado, G., 25 Yamazaki, Y., 123 Tiwari, D., 22, 28, 33 Yee, J., 46 Tiwari, P., 22 Yee, S., 35 Tsugawa, T., 38, 56 Yizengaw, E., 61, 90, 101, 117, 121 Tsunoda, R., 10, 20, 99, 117 Yokoyama, T., 31, 102

129 ISEA13 - 13th International Symposium on Equatorial Aeronomy

Yumoto, K., 123

Z Zablowski, P., 68, 108 Zakharenkova, I., 32, 85, 90, 118 Zesta, E., 90, 101 Zhang, X., 40 Zhao, B., 79 Zhao, Y., 66 Zhu, X., 35, 46

130 ISEA13 - 13th International Symposium on Equatorial Aeronomy

ORGANIZING AND COLLABORATING INSTITUTIONS