DOCSLIB.ORG

The Magnetosphere-Ionosphere Electron Precipitation Dynamics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Magnetosphere-Ionosphere Electron Precipitation Dynamics RESEARCH ARTICLE The Magnetosphere‐Ionosphere Electron Precipitation 10.1029/2019JA026589 Dynamics and Their Geospace Consequences Key Points: • Simulated magnetospheric During the 17 March 2013 Storm dynamics depends on the pattern George V. Khazanov1 , Margaret W. Chen2 , Colby L. Lemon2 , and David G. Sibeck1 and intensity of electrons precipitating into the atmosphere 1NASA Goddard Space Flight Center, Greenbelt, MD, USA, 2The Aerospace Corporation, El Segundo, CA, USA • Precipitating electron energy fluxes enhanced by multiple atmospheric reflections affect ionospheric conductance Abstract During geomagnetic storms and substorms, the magnetosphere and ionosphere are strongly • Reduced electric field shielding at coupled by precipitating magnetospheric electrons from the Earth's plasma sheet and driven by both low L can lead to an increase in magnetospheric and ionospheric processes. Magnetospheric wave activity initiates electron precipitation, modeled ring current energy content and the ionosphere and upper atmosphere further facilitate this process by enhancing the value of precipitated energy fluxes via connection of two magnetically conjugate regions and multiple atmospheric reflections. This paper focuses on the resulting electron energy fluxes and affiliated height‐integrated Correspondence to: fl G. V. Khazanov, Pedersen and Hall conductances in the auroral regions produced by multiple atmospheric re ections during [email protected] the 17 March 2013 geomagnetic storm and their effects on the inner magnetospheric electric field and ring current. Our study is based on the magnetically and electrically self‐consistent Rice Convection ‐ fi Citation: Model Equilibrium of the inner magnetosphere with SuperThermal Electron Transport modi ed electron Khazanov, G. V., Chen, M. W., Lemon, energy fluxes that take into account the electron energy interplay between the two magnetically conjugate C. L., & Sibeck, D. G. (2019). The ionospheres. SuperThermal Electron Transport‐modified energy flux in the Rice Convection ‐ magnetosphere ionosphere electron ‐ fi precipitation dynamics and their Model Equilibrium leads to a signi cant difference in the global conductance pattern, ionospheric electric geospace consequences during the 17 field formation, Birkeland current structure, ring current energization and its energy content, subauroral March 2013 storm. Journal of polarization drifts intensifications and their spatial locations, interchange instability redistribution, and Geophysical Research: Space Physics, 124. https://doi.org/10.1029/ overall energy interplay on the global scale. 2019JA026589 Received 1 FEB 2019 1. Introduction Accepted 11 JUN 2019 Accepted article online 26 JUN 2019 The importance of ionospheric conductivity in coupling magnetospheric and ionospheric plasmas has been recognized since the early days of space science. Wolf (1970) and Vasyliunas (1970) used the ionospheric Ohm's law to calculate the electric field distribution governing magnetospheric plasma circulation. The central importance of ionospheric electrodynamics and conductivity in governing magnetosphere‐ ionosphere‐thermosphere dynamics is evident across a broad range of solar terrestrial science topics: for example, thermospheric responses to geomagnetic storms (Wang et al., 2008), conductivity correlations with dayside field‐aligned currents (Ohtani et al., 2005), global magnetosphere configuration (Ridley et al., 2004), substorm dynamics (Raeder et al., 2001), ring current dynamics (Chen et al., 2015; Ebihara et al., 2004), sub- auroral polarization drifts (SAPS; Anderson et. al., 1993; Zheng et al., 2008; Huba et al., 2017; Mishin et al., 2017), and plasma sheet fast‐flow dynamics (Zhang et al., 2012). Ionospheric conductance depends strongly on particle precipitation into the atmosphere. Both ions and electrons precipitate in the aurora; however, the average integral number flux of the precipitating auroral ions is typically 1 to 2 orders of magnitude less than that of the precipitating auroral electrons (Hardy et al., 1989). Simulations of Chen et al. (2019) of electron precipitation (due to wave scattering) and ion precipitation (due to field line curvature) during a large storm showed that precipitating electrons are the dominant contributor to auroral conductance. Therefore, the electron precipitating flux requires careful examination. Chen et al. (2015) noted “The simulated stormtime ring current energization can vary significantly depending on the ionospheric conductance and electron loss model used. Thus, it is important to incorporate realistic descriptions of ionospheric conductance and electron losses in inner magnetospheric models.” Early simulations of diffuse electron auroral precipitation assumed strong pitch angle scattering ©2019. American Geophysical Union. everywhere with perhaps a constant fraction of backscatter (Chen & Schulz, 2001; Fontaine & Blanc, This article has been contributed to by 1983; Wolf et al., 1982). Chen, Lemon, Orlova, et al. (2015) showed that strong pitch angle scattering caused US Government employees and their fl work is in the public domain in the electron losses that were too rapid to account for observed trapped electron uxes at Geosynchronous orbit. USA. Recent models of Chen et al. (2019), Chen, Lemon, Orlova, et al. (2015), and Yu et al. (2016) that include KHAZANOV ET AL. 1 Journal of Geophysical Research: Space Physics 10.1029/2019JA026589 more realistic electron losses of pitch angle scattering with chorus waves have been able to reproduce rea- sonably well observed diffuse precipitating electron energy fluxes near dawn during storm events. However, further work is needed to characterize global patterns of electron precipitation. During geomagnetic storms and substorms, the magnetosphere and ionosphere are strongly coupled by pre- cipitating magnetospheric electrons from the Earth's plasma sheet. As has been shown by Khazanov et al. (2014) about 15–40% of the total aurora energy returns back to the magnetosphere and the conjugate iono- sphere. Collisionless processes dominate in the inner magnetosphere, whereas collisional interactions are important in the ionosphere, and Khazanov et al. (2018) have emphasized that first‐principle simulations of precipitating electron fluxes in both regimes are required to understand spatial and temporal variations of ionospheric conductance and related electric fields. As discussed by Khazanov et al. (2015), Khazanov, Glocer et al. 2016, 2017a), the first step in such simulations is initiation of electron precipitation from the Earth's plasma sheet via wave‐particle interactions (WPIs) into both magnetically conjugate points (e.g., as is simulated by Chen, Lemon, Guild, et al., 2015). The second step is to account for multiple atmospheric reflections of electrons between the ionosphere and magnetosphere at the two magnetically conjugate points, as treated in the SuperThermal Electron Transport (STET) model (Khazanov et al., 2015, 2017a, 2017b, 2018; Khazanov, Glocer, et al., 2016; Khazanov, Himwich, et al., 2016). This paper focuses on the resulting electron energy fluxes and affiliated height‐integrated Pedersen and Hall conductances in the auroral regions produced by multiple atmospheric reflections during the large 17 March 2013 geomagnetic storm and their effects on the inner magnetospheric electric field and ring current. Our study is based on the Aerospace version of the magnetically and electrically self‐consistent Rice Convection Model‐Equilibrium (RCM‐E) of the inner magnetosphere (Chen, Lemon, Guild, et al., 2015), with STET‐modified electron energy fluxes that take into account the electron energy interplay between the two magnetically conjugate ionospheres. 2. Role of MI Coupling in Electron Precipitation Formation In the aurora, precipitating electrons driven by WPI in the Earth's plasma sheet collide with atmospheric molecules, lose energy, and produce secondary electrons (SEs) via impact ionization. The precipitating and SEs can also reflect back into the magnetosphere and then undergo multiple reflections at the magnetic conjugate points. As was shown by Khazanov et al. (2015–2018), these processes greatly influence the total precipitating flux at the upper ionospheric boundary (around about 800 km). The resultant populations of secondary and primary electrons undergo both elastic and inelastic collisions with the neutral atmosphere, cascading toward lower energies and reflecting back to the magnetosphere. Those electrons reflected upward from the ionosphere can be trapped in the magnetosphere if they scatter out of the loss cone via cou- lomb collisions with the cold plasma or through interactions with different kinds of plasma waves. In situ measurements of the precipitating electron energy flux spectra in the ionosphere naturally include all these effects. However, the physics of multiple reflections and scattering has been missing in aurora global mod- eling research, and in this study we add this capability to RCM‐E simulations and examine the effects on inner magnetospheric plasma transport and the electric and magnetic fields. The STET code models all sources and collisional processes of electrons as they travel along a magnetic field line through the magnetosphere and ionosphere (Khazanov et al., 2015; Khazanov, Glocer, et al., 2016; Khazanov, Himwich, et al., 2016; Khazanov et al., 2017b) with participation of both magnetically conjugate regions. It simulates nonsteady formation of electron distribution functions kinetically along 1‐D in space and 2‐D in velocity
Load more

Recommended publications
  • E-Region Auroral Ionosphere Model
    atmosphere Article AIM-E: E-Region Auroral Ionosphere Model Vera Nikolaeva 1,* , Evgeny Gordeev 2 , Tima Sergienko 3, Ludmila Makarova 1 and Andrey Kotikov 4 1 Arctic and Antarctic Research Institute, 199397 Saint Petersburg, Russia; [email protected] 2 Earth’s Physics Department, Saint Petersburg State University, 199034 Saint Petersburg, Russia; [email protected] 3 Swedish Institute of Space Physics, 981 28 Kiruna, Sweden; [email protected] 4 Saint Petersburg Branch of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of Russian Academy of Sciences (IZMIRAN), 199034 Saint Petersburg, Russia; [email protected] * Correspondence: [email protected] Abstract: The auroral oval is the high-latitude region of the ionosphere characterized by strong vari- ability of its chemical composition due to precipitation of energetic particles from the magnetosphere. The complex nature of magnetospheric processes cause a wide range of dynamic variations in the auroral zone, which are difficult to forecast. Knowledge of electron concentrations in this highly turbulent region is of particular importance because it determines the propagation conditions for the radio waves. In this work we introduce the numerical model of the auroral E-region, which evaluates density variations of the 10 ionospheric species and 39 reactions initiated by both the solar extreme UV radiation and the magnetospheric electron precipitation. The chemical reaction rates differ in more than ten orders of magnitude, resulting in the high stiffness of the ordinary differential equations system considered, which was solved using the high-performance Gear method. The AIM-E model allowed us to calculate the concentration of the neutrals NO, N(4S), and N(2D), ions + + + + + 4 + 2 + 2 N ,N2 , NO ,O2 ,O ( S), O ( D), and O ( P), and electrons Ne, in the whole auroral zone in the Citation: Nikolaeva, V.; Gordeev, E.; 90-150 km altitude range in real time.
    [Show full text]
  • Global X-Ray Emission During an Isolated Substorm Р a Case Study
    Journal of Atmospheric and Solar-Terrestrial Physics 62 (2000) 889±900 Global X-ray emission during an isolated substorm Ð a case study N. éstgaard a,*, J. Stadsnes a, J. Bjordal a, R.R. Vondrak b, S.A. Cummer b, D.L. Chenette c, M. Schulz c, G.K. Parks d, M.J. Brittnacher d, D.L. McKenzie e, J.G. Pronko f aDepartment of Physics, University of Bergen, Bergen, Norway bLaboratory for Extraterrestrial Physics, Goddard Space Flight Center, Greenbelt, MD, USA cLockheed-Martin Advanced Technology Center, Palo Alto, CA, USA dGeophysics Program, University of Washington, Seattle, WA, USA eThe Aerospace Corporation, Los Angeles, CA, USA fPhysics Department, University of Nevada, Reno, NV, USA Received 30 July 1999; accepted 10 December 1999 Abstract The polar ionospheric X-ray imaging experiment (PIXIE) and the UV imager (UVI) onboard the Polar satellite have provided the ®rst simultaneous global scale views of the patterns of electron precipitation through imaging of the atmospheric X-ray bremsstrahlung and the auroral UV emissions. While the UV images in the Lyman±Birge± Hop®eld-long band used in this study respond to the total electron energy ¯ux which is usually dominated by low- energy electrons (<10 keV), the PIXIE images of X-ray bremsstrahlung above 02.7 keV respond to electrons of energy above 03 keV. Comparison of precipitation features seen by UVI and PIXIE provides information on essentially complementary energy ranges of the precipitating electrons. In this study an isolated substorm is examined using data from PIXIE, UVI, ground-based measurements, and in situ measurements from high- and low- altitude satellites to obtain information about the global characteristics during the event.
    [Show full text]
  • Pitch Angle Dependence of Energetic Electron Precipitation: Energy
    Confidential manuscript submitted to JGR 1 Pitch Angle Dependence of Energetic Electron Precipitation: 2 Energy Deposition, Backscatter, and the Bounce Loss Cone 1 2 3 R. A. Marshall and J. Bortnik 1 4 Ann and H. J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO 5 80309, USA. 2 6 Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, CA 90095, USA. 7 Key Points: • 8 We characterize energy deposition and atmospheric backscatter of radiation belt 9 electrons as a function of energy and pitch angle • 10 We use these simulations to characterize the bounce loss cone and show that it is 11 energy dependent • 12 The simulated backscatter of precipitation is characterized by field aligned beams 13 of low energies which should be observable Corresponding author: R. A. Marshall, [email protected] –1– Confidential manuscript submitted to JGR 14 Abstract 15 Quantifying radiation belt precipitation and its consequent atmospheric effects re- 16 quires an accurate assessment of the pitch angle distribution of precipitating electrons, as 17 well as knowledge of the dependence of the atmospheric deposition on that distribution. 18 Here, Monte Carlo simulations are used to investigate the effects of the incident electron 19 energy and pitch angle on precipitation for bounce-period time scales, and the implica- 20 tions for both the loss from the radiation belts and the deposition in the upper atmosphere. 21 Simulations are conducted at discrete energies and pitch angles to assess the dependence 22 on these parameters of the atmospheric energy deposition profiles and to estimate the 23 backscattered particle distributions.
    [Show full text]
  • On Magnetic Storms and Substorms
    ILWS WORKSHOP 2006, GOA, FEBRUARY 19-24, 2006 On magnetic storms and substorms G. S. Lakhina, S. Alex, S. Mukherjee and G. Vichare Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218, India Abstract. Magnetospheric substorms and storms are indicators of geomagnetic activity. Whereas the geomagnetic index AE (auroral electrojet) is used to study substorms, it is common to characterize the magnetic storms by the Dst (disturbance storm time) index of geomagnetic activity. This talk discusses briefly the storm-substorms relationship, and highlights some of the characteristics of intense magnetic storms, including the events of 29-31 October and 20-21 November 2003. The adverse effects of these intense geomagnetic storms on telecommunication, navigation, and on spacecraft functioning will be discussed. Index Terms. Geomagnetic activity, geomagnetic storms, space weather, substorms. _____________________________________________________________________________________________________ 1. Introduction latitude magnetic fields are significantly depressed over a Magnetospheric storms and substorms are indicators of time span of one to a few hours followed by its recovery geomagnetic activity. Where as the magnetic storms are which may extend over several days (Rostoker, 1997). driven directly by solar drivers like Coronal mass ejections, solar flares, fast streams etc., the substorms, in simplest terms, are the disturbances occurring within the magnetosphere that are ultimately caused by the solar wind. The magnetic storms are characterized by the Dst (disturbance storm time) index of geomagnetic activity. The substorms, on the other hand, are characterized by geomagnetic AE (auroral electrojet) index. Magnetic reconnection plays an important role in energy transfer from solar wind to the magnetosphere. Magnetic reconnection is very effective when the interplanetary magnetic field is directed southwards leading to strong plasma injection from the tail towards the inner magnetosphere causing intense auroras at high-latitude nightside regions.
    [Show full text]
  • Pos(ICRC2017)086 Eric Cascade: Electron Del
    Computation of electron precipitation atmospheric ionization: updated model CRAC-EPII Alexander Mishev∗ PoS(ICRC2017)086 Space Climate Research Unit, University of Oulu, Finland. E-mail: [email protected] Anton Artamonov Space Climate Research Unit, University of Oulu, Finland. E-mail: [email protected] Genady Kovaltsov Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg, Russia. E-mail: [email protected] Irina Mironova St. Petersburg State University, Institute of Physics, St. Petersburg, Russia E-mail: [email protected] Ilya Usoskin Space Climate Research Unit; Sodankylä Geophysical Observatory (Oulu unit), University of Oulu, Finland. E-mail: [email protected] A new model of the CRAC family, CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) is presented. The model allows one to calculate atmospheric ionization induced by precipitating electrons. The model is based on pre-computed with high- precision ionization yield functions, which are obtained using full Monte Carlo simulation of electron propagation and interaction in the Earth’s atmosphere, explicitly considering all physical processes involved in ion production. The simulations were performed using GEANT 4 simu- lation tool PLANETOCOSMICS with NRLMSISE 00 atmospheric model. A quasi-analytical approach, which allows one to compute the ionization yields for events with arbitrary incidence is also presented. It is compared with Monte Carlo simulations and good agreement between Monte Carlo simulations and quasi-analytical approach is achieved. 35th International Cosmic Ray Conference - ICRC 2017- 10-20 July, 2017 Bexco, Busan, Korea ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).
    [Show full text]
  • Space Weather and Real-Time Monitoring
    Data Science Journal, Volume 8, 30 March 2009 SPACE WEATHER AND REAL-TIME MONITORING S Watari National Institute of Information and Communications Technology, 4-2-1 Nukuikita, Koganei, Tokyo 184-8795, Japan Email: [email protected] ABSTRACT Recent advance of information and communications technology enables to collect a large amount of ground-based and space-based observation data in real-time. The real-time data realize nowcast of space weather. This paper reports a history of space weather by the International Space Environment Service (ISES) in association with the International Geophysical Year (IGY) and importance of real-time monitoring in space weather. Keywords: Space Weather, Real-time Monitoring, International Space Environment Service (ISES) 1 INTRODUCTION The International Geophysical Year (IGY) took place between 1957 and 1958. In the IGY, the first artificial satellite, Sputnik 1, was launched on 4 October, 1957. After approximately 50 years since the Sputnik, now we use many satellites for communication, broadcast, navigation, meteorological observation, and so on. After several failures of satellites, we notice that we can not neglect the space environment, which affects manmade technology systems. It is called “space weather.” Researches of space weather are on going all over the world now. During the IGY, the information of Alert and Special World Interval (SWI) was exchanged among participated institutes for coordinated observations of the Sun and geophysical environment. The Alert was distributed whenever solar activity is unusually high and significant geomagnetic, auroral, ionospheric or cosmic ray effects are probable. The SWI was distributed whenever a possibility of an outstanding geomagnetic storm is high during the period of the Alert.
    [Show full text]
  • Electron Precipitation Models in Global Magnetosphere Simulations
    JournalofGeophysicalResearch: SpacePhysics RESEARCH ARTICLE Electron precipitation models in global 10.1002/2014JA020615 magnetosphere simulations 1 1 1 2 3 Key Points: B. Zhang ,W.Lotko , O. Brambles , M. Wiltberger , and J. Lyon • Electron precipitation models are developed for global magnetosphere 1Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA, 2High Altitude Observatory, National simulations Center for Atmospheric Research, Boulder, Colorado, USA, 3Department of Physics and Astronomy, Dartmouth College, • Monoenergetic and diffuse Hanover, New Hampshire, USA precipitation exhibit nonlinear relations with SW driving • Modeled precipitation power is consistent with estimations from Abstract General methods for improving the specification of electron precipitation in global simulations UVI images are described and implemented in the Lyon-Fedder-Mobarry (LFM) global simulation model, and the quality of its predictions for precipitation is assessed. LFM’s existing diffuse and monoenergetic electron Correspondence to: precipitation models are improved, and new models are developed for lower energy, broadband, and B. Zhang, direct-entry cusp precipitation. The LFM simulation results for combined diffuse plus monoenergetic [email protected] electron precipitation exhibit a quadratic increase in the hemispheric precipitation power as the intensity of solar wind driving increases, in contrast with the prediction from the OVATION Prime (OP) 2010 empirical Citation: precipitation model which increases linearly with driving intensity. Broadband precipitation power increases Zhang,B.,W.Lotko,O.Brambles, M. Wiltberger, and J. Lyon (2015), approximately linearly with driving intensity in both models. Comparisons of LFM and OP predictions with Electron precipitation models estimates of precipitating power derived from inversions of Polar satellite UVI images during a double in global magnetosphere substorm event (28–29 March 1998) show that the LFM peak precipitating power is > 4× larger when using simulations, J.
    [Show full text]
  • Ring Current Coupling: a Comparison of Isolated and Compound Substorms
    manuscript submitted to JGR: Space Physics 1 Substorm - Ring Current Coupling: A comparison of 2 isolated and compound substorms 1 1 2 3 1 3 J. K. Sandhu , I. J. Rae ,M.P.Freeman , M. Gkioulidou , C. Forsyth ,G. 4 5 6 4 D. Reeves ,K.R.Murphy , M.-T. Walach 1 5 Department of Space and Climate Physics, Mullard Space Science Laboratory, University College 6 London, Dorking, RH5 6NT, UK. 2 7 British Antarctic Survey, Cambridge, CB3 0ET, UK. 3 8 Applied Physics Laboratory, John Hopkins University, Maryland, USA. 4 9 Los Alamos National Laboratory, Los Alamos, USA. 5 10 University of Maryland, USA. 6 11 Lancaster University, LA1 4YW, UK. 12 Key Points: 13 • Quantitative estimates of ring current energy for compound and isolated substorms 14 are shown. 15 • The energy content and post-onset enhancement is larger for compound compared 16 to isolated substorms. 17 • Solar wind coupling is a key driver for di↵erences in the ring current between iso- 18 lated and compound substorms. Corresponding author: Jasmine K. Sandhu, [email protected] –1– manuscript submitted to JGR: Space Physics 19 Abstract 20 Substorms are a highly variable process, which can occur as an isolated event or as part 21 of a sequence of multiple substorms (compound substorms). In this study we identify 22 how the low energy population of the ring current and subsequent energization varies 23 for isolated substorms compared to the first substorm of a compound event. Using ob- + + 24 servations of H and O ions (1 eV to 50 keV) from the Helium Oxygen Proton Elec- 25 tron instrument onboard Van Allen Probe A, we determine the energy content of the ring 26 current in L-MLT space.
    [Show full text]
  • 1. State of the Magnetosphere
    VOL. 78, NO. 16 3OURNAL OF GEOPHYSICAL RESEARCH 3UNE 1, 1973 SatelliteStudies of MagnetosphericSubstorms on August15, 1968 1. Stateof the Magnetosphere R. L. M CPHERRON Department o] Planetary and SpaceScience and Institute o] Geophysicsand Planetary Physics University o] California, Los Angeles,California 90024 The sequenceof eventsoccurring throughou.t the magnetosphereduring a substormhas not been precisely determined. This paper introduces a collection.of papers that attempts to establish this sequencefor two substormson August 15, 1968. Data from a wide variety of sourcesare used, the major emphasisbeing changesin the magnetic field. In this paper we use ground magnetograms to determine the onset times of two substorms that occurred while the Ogo 5 satellite was inbound on the midnight meridian through the cusp region of the geomagnetictail (the region of rapid changefrom taillike to dipolar field). We concludethat at least two worldwide substormexpansions were precededby growth phases.Probable begin- nings of these phaseswere at 0330 and 0640 UT. However, the onset of the former growth phase was partially obscuredby the effects of a preceding expansionphase around 0220 and a possible localized event in the auroral zone near 0320 UT. The onsets of the cor- respondingexpansion phases were 0430 and 0714 UT. Further support for these determina- tions is provided by data discussedin the subsequentnotes. The precise sequenceof events that occurs Ogo 5 in the near tail, and ATS I at syn- during a magnetosphericsubstorm has not been chronousorbit. Solar wind plasma parameters established.Among the reasons for this are were measured by Vela 4A. Magnetospheric lack of consistencyin the definition of sub- convection is inferred from a combination of storm onset and the wide variability of suc- plasmapauseobservations on Ogo 4 and 5 in cessivesubstorms.
    [Show full text]
  • Sign-Singularity Analysis of Field-Aligned Currents in the Ionosphere
    atmosphere Article Sign-Singularity Analysis of Field-Aligned Currents in the Ionosphere Giuseppe Consolini 1,* , Paola De Michelis 2 , Igino Coco 2 , Tommaso Alberti 1 , Maria Federica Marcucci 1 , Fabio Giannattasio 2 and Roberta Tozzi 2 1 INAF-Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, 00133 Rome, Italy; [email protected] (T.A.); [email protected] (M.F.M.) 2 Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy; [email protected] (P.D.M.); [email protected] (I.C.); [email protected] (F.G.); [email protected] (R.T.) * Correspondence: [email protected] Abstract: Field-aligned currents (FACs) flowing in the auroral ionosphere are a complex system of upward and downward currents, which play a fundamental role in the magnetosphere–ionosphere coupling and in the ionospheric heating. Here, using data from the ESA-Swarm multi-satellite mission, we studied the complex structure of FACs by investigating sign-singularity scaling features for two different conditions of a high-latitude substorm activity level as monitored by the AE index. The results clearly showed the sign-singular character of FACs supporting the complex and filamentary nature of these currents. Furthermore, we found evidence of the occurrence of a topological change of these current systems, which was accompanied by a change of the scaling features at spatial scales larger than 30 km. This change was interpreted in terms of a sort of Citation: Consolini, G.; De Michelis, P.; Coco, I.; Alberti, T.; Marcucci, M.F.; symmetry-breaking phenomenon due to a dynamical topological transition of the FAC structure as a Giannattasio, F.; Tozzi, R.
    [Show full text]
  • The Role of Localized Compressional Ultra-Low Frequency Waves In
    PUBLICATIONS Journal of Geophysical Research: Space Physics RESEARCH ARTICLE The Role of Localized Compressional Ultra-low Frequency 10.1002/2017JA024674 Waves in Energetic Electron Precipitation Key Points: I. Jonathan Rae1 , Kyle R. Murphy2 , Clare E. J. Watt3 , Alexa J. Halford4 , Ian R. Mann5 , • We detail a new mechanism for direct 5 2 6 7 modulation of electron precipitation Louis G. Ozeke , David G. Sibeck , Mark A. Clilverd , Craig J. Rodger , 8 1 9 via localized compressional waves Alex W. Degeling , Colin Forsyth , and Howard J. Singer • Electrons encountering a time-varying and spatially localized ULF wave can 1Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, UK, break the third invariant 2NASA Goddard Space Flight Centre, Greenbelt, MD, USA, 3Department of Meteorology, University of Reading, Reading, UK, • This localized mechanism has not 4Space Sciences Department, The Aerospace Corporation, Chantilly, VA, USA, 5Department of Physics, University of Alberta, previously been considered and may 6 7 be important for radiation belt losses Edmonton, Alberta, Canada, British Antarctic Survey (NERC), Cambridge, UK, Department of Physics, University of Otago, Dunedin, New Zealand, 8Institute of Space Science and Physics, Shandong University, Weihai, China, 9Space Weather Prediction Center, NOAA, Boulder, CO, USA Supporting Information: • Supporting Information S1 Correspondence to: Abstract Typically, ultra-low frequency (ULF) waves have historically been invoked for radial diffusive I. J. Rae, transport leading to acceleration and loss of outer radiation belt electrons. At higher frequencies, very low [email protected] frequency waves are generally thought to provide a mechanism for localized acceleration and loss through precipitation into the ionosphere of radiation belt electrons.
    [Show full text]
  • A Profile of Space Weather
    A Profile of Space Weather Space weather describes the conditions in space that affect Earth and its technological systems. Space weather is a consequence of the behavior of the Sun, the nature of Earth’s magnetic field and atmosphere, and our location in the solar system. The active elements of space weather are particles, electromagnetic energy, and magnetic field, rather than the more commonly known weather contributors of water, temperature, and air. The Space Weather Prediction Center (SWPC) forecasts space weather to assist users in avoiding or mitigating severe space weather. Most disruptions caused by space weather storms affect technology, With the rising sophistication of our technologies, and the number of people that rely on this technology, vulnerability to space weather events has increased dramatically. Geomagnetic Storms Induced Currents in the atmosphere and on the ground Electric Power Grid systems suffer (black-outs) Pipelines carrying oil, for instance, can be damaged by the high currents. Electric Charges in Space Solar Radiation Storms Satellites may encounter problems with the on- board components and electronic systems. Hazard to Humans Geomagnetic disruption in the upper atmosphere High radiation hazard to astronauts HF (high frequency) radio interference Less threathening, but can effect high-flying aircraft at high latitudes Satellite navigation (like GPS receivers) may be degraded Damage to Satellites Satellites can slow and even change orbit. High-energy particles can render satellites useless (either temporarily or permanently) The Aurora can be seen in high latitudes Impact on Communications HF communications as well as Low Frequency Navigation Signals are susceptible to radiation storms. HF communication at high latitudes is often impossible for several days during radiation storms Space Weather Prediction Center The Space Weather Prediction Center (SWPC) Forecast Center is jointly operated by NOAA and the U.S.
    [Show full text]