DOCSLIB.ORG

SCIAMACHY Limb Measurements in the UV/Vis Spectral Region: First Results

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
SCIAMACHY Limb Measurements in the UV/Vis Spectral Region: First Results Advances in Space Research 34 (2004) 775–779 www.elsevier.com/locate/asr SCIAMACHY limb measurements in the UV/Vis spectral region: first results K.-U. Eichmann a,*, J.W. Kaiser b, C. von Savigny a, A. Rozanov a, V.V. Rozanov a, H. Bovensmann a, M. von Konig€ a, J.P. Burrows a a Institute of Environmental Physics, University of Bremen, FB 1, D-28334 Bremen, Germany b Remote Sensing Laboratories, University of Zurich, Switzerland Received 1 December 2002; received in revised form 15 May 2003; accepted 23 May 2003 Abstract Stratospheric density profile measurements of ozone and nitrogen dioxide derived from limb scattered radiance spectra mea- surements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are presented in this paper. SCIAMACHY is part of the ENVISAT satellite instrumentation, which has been successfully launched in March 2002. SCIAMACHY determines both the total amount and vertical density distributions of a large number of atmospheric constituents by measuring the Earthshine radiance, simultaneously from the ultraviolet (UV) to the near infrared (NIR), in the three viewing ge- ometries nadir, limb, and occultation. The results of the trace gas retrievals of ozone and nitrogen dioxide are compared with nearby POAM III measurements as a first step of verification. Ó 2004 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: SCIAMACHY; Stratospheric density profile measures; Ozone; Stratospheric nitrogen diozide 1. Introduction limited horizontal coverage of occultation experiments like HALogen Occultation Experiment (HALOE) The SCanning Imaging Absorption SpectroMeter for (Russell et al., 1993), Polar Ozone and Aerosol Mea- Atmospheric CHartographY (SCIAMACHY) instru- surement (POAM) (Lucke et al., 1999), and Strato- ment is a space-based spectrometer (Burrows and spheric Aerosols and Gas Experiment (SAGE) Chance, 1991) launched on board ENVIronmental (McCormick et al., 1989). The limb scatter technique SATellite (ENVISAT) in March 2002 (see e.g. Bovens- has previously been used by the Limb Ozone Retrieval mann et al., 1999). SCIAMACHY employs three dis- Experiment/Shuttle Ozone Limb Sounding Experiment tinct viewing modes during each orbit cycle to measure (LORE/SOLSE) instruments flown in 1997 on NASA’s the sun light scattered and absorbed by the Earth’s at- space shuttle mission STS-87 (Flittner et al., 2000). It mosphere: nadir, limb, and occultation. has been also applied to the measurements of the Op- The limb viewing mode of SCIAMACHY is used to tical Spectrograph and Infrared Imager System (OSI- overcome the limited vertical resolution of retrieved RIS) (Llewellyn et al., 1997) aboard the Odin satellite trace gas profiles from nadir viewing spectrometers like (Murtagh et al., 2002) launched in February 2001. the Global Ozone Monitoring Experiment (GOME) This paper, presents first results of both ozone and (Burrows et al., 1999; Hoogen et al., 1999) and the nitrogen dioxide density profiles retrieved from SCIAMACHY limb scatter measurements. To verify the limb retrieval algorithm, first comparisons with trace gas * Corresponding author. Tel.: +49-427-218-4352; fax: +49-421-218- 4555. profiles of the POAM III occultation instrument on E-mail address: [email protected] board the French SPOT-4 satellite (Lucke et al., 1999) (K.-U. Eichmann). were made. 0273-1177/$30 Ó 2004 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2003.05.057 776 K.-U. Eichmann et al. / Advances in Space Research 34 (2004) 775–779 2. The SCIAMACHY instrument which takes both the sphericity of the atmosphere and two orders of scattering into account. Radiance and SCIAMACHY is a passive remote-sensing spec- weighting functions are calculated from analytical for- trometer detecting light in the wavelength range from mulae (Kaiser, 2001). the ultraviolet (240 nm) to the near infrared (2380 nm) A non-linear optimal estimation approach was used with moderate resolution (0.24–1.48 nm). This spectral to derive the ozone profiles. One method (Savigny) is range is divided into eight channels, each science chan- based on the comparison of normalized and paired limb nel comprises 1024 pixel. Thus approximately 8000 radiances for each tangent height both in the center and spectral points are recorded simultaneously. For most of in the wings of the Chappuis–Wulf ozone absorption the orbit, SCIAMACHY makes alternating nadir and bands (525, 600, 675 nm, averaged over 2 nm) (Flittner limb measurements. et al., 2000; McPeters et al., 2000; von Savigny, 2002). In limb viewing mode, SCIAMACHY is looking The other retrieval method (Rozanov) is based on the forward into the flight direction, scanning the atmo- simultaneous fitting of wavelengths from 520 to 670 nm. sphere horizontally and vertically. The instantaneous Employing the Chappuis bands for O3 profile retrievals field-of-view (IFOV) for the limb mode is 0.045° verti- the altitude range between about 15 and 40 can be cally and 1.8° horizontally, corresponding to a geomet- sensed. Below 15 km the line of sight optical depth be- rical field-of-view at the tangent point of 2.6 and 110 comes so large, that retrievals from SCIAMACHY km, respectively. One limb cycle has a total duration of measurements are not reliable down to the troposphere. 60 s. Each horizontal (azimuth) scan has a duration of Above 40 km the absorption signature is too weak for 1.5 s and is divided into up to four individual scans retrievals at this wavelength range. Using an optimal depending on the intensity of the radiance as a function estimation approach the retrieval results are mostly in- of the wavelength. Thus the spatial resolution in across fluenced by the a priori profiles at these heights. Using track (azimuth) direction is typically 240 km, deter- the UV absorption features of ozone around 260 nm, a mined by the integration time. A total of 35 vertical scan retrieval of ozone up to about 75 km will be possible. steps are made. Starting at about )3 km tangent height, Temperature dependent SCIAMACHY Flight Model the tangent height step size is typically 3.3 km. 34 hor- ozone cross-sections and a latitude and time dependent izontal scan steps up to 100 km altitude are performed MPI climatology atmosphere were used as input pa- and one dark signal measurement at about 150 km al- rameter for the forward models, the ground albedo was titude. The horizontal scans are covering 960 km in taken to be A ¼ 0.3. Systematic errors of less than 4% across-track direction. The light path in along track can be expected due to an incorrect albedo (von Savigny direction is approximately 400 km. More details on the et al., 2003). Stratospheric background aerosol profiles characteristics of the SCIAMACHY instrument and the and optical properties are taken from the LOWTRAN-7 data products can be found in e.g. Bovensmann et al. aerosol model (Kneizys et al., 1988). About 2% percent (1999). difference in the retrieved ozone density in the strato- sphere can be expected between using the single scat- tering approximation of SCIARAYS and the full 3. Data and methods multiple scattering forward model SCIATRAN-CDIPI. Below the ozone peak the relative errors will be bigger. For this paper, the raw level zero SCIAMACHY data The NO2 retrieval is performed in the spectral were used, which is the signal (counts) integrated over range 420–455 nm using a ratio of limb measurements the whole azimuth scan of 960 km to get a better signal- at different tangent heights. A measurement at a tan- to-noise ratio. The data are divided by the integration gent height of 40 km is used as a reference spectrum. times (s) and a preliminary dark current correction is The model spectra are calculated using the CDI radi- performed by subtracting the spectrum at 150 km tan- ative transfer model and the optimal estimation gent height. To eliminate the effects of the solar Fra- method is used for the retrieval. Only measurements at unhofer structure and multiplicative instrumental tangent heights between 10 and 40 km are taken into artifacts, the signal is divided by the spectrum at about account. 50 km tangent height. The polarization sensitivity of the instrument is not taken into account. The tangent height information is taken from the operational data product. 4. Results Two forward models were used to simulate the limb scattered radiances. The spherical version of SCIA- Limb radiance profiles were recorded by SCIAM- TRAN (Rozanov et al., 2001) is based on a new Com- ACHY on April 25, 2002 over North America to derive bining Differential-Integral approach using the Picard the vertical ozone distribution. In Fig. 1 the flight path Iterative approximation (CDIPI) (Rozanov et al., 1998, of ENVISAT and the points of limb measurements are 2001). SCIARAYS is a fast radiative transfer model plotted over a total ozone map from the ERS-2 GOME K.-U. Eichmann et al. / Advances in Space Research 34 (2004) 775–779 777 ozone number densities (cmÀ3) as a function of altitude (km) between 10 and 40 km are also compared to the measurements of the POAM III occultation sensor. POAM III has a slightly better vertical resolution of 1–2 km in the stratosphere (Lucke et al., 1999) and is vali- dated against ozone sondes and other satellite mea- surements. All three profiles agree fairly well (within 10%) taken the different vertical resolution and the dif- ferences in viewing geometry, geolocation and mea- surement time into account. POAM has a three times higher vertical resolution leading to more features in the profile. It also has completely different viewing angles, so even if the tangent points of both instruments are at the same place and time, they will see different air masses. The result of this effect is hard to quantify from one measurement alone and has to be studied in a comprehensive validation campaign which is beyond the scope of this paper.
Load more

Recommended publications
  • World Meteorological Organization Global Atmosphere Watch
    WORLD METEOROLOGICAL ORGANIZATION GLOBAL ATMOSPHERE WATCH No. 140 WMO/CEOS REPORT on a STRATEGY for INTEGRATING SATELLITE and GROUND-BASED OBSERVATIONS of OZONE JANUARY 2001 WORLD METEOROLOGICAL ORGANIZATION GLOBAL ATMOSPHERE WATCH No. 140 WMO/CEOS REPORT on a STRATEGY for INTEGRATING SATELLITE and GROUND-BASED OBSERVATIONS of OZONE WMO TD No. 1046 List of Contents Foreword ...................................................................................................................................... iii Executive Summary...................................................................................................................... v Milestones in the History of Ozone ............................................................................................ ix 1. Introduction.......................................................................................................................... 1 1.1 The IGOS Strategy ................................................................................................. 1 1.2 The Ozone Project.................................................................................................. 2 1.3 Requirements and Data Sources .......................................................................... 5 1.4 The Objectives of the Report ................................................................................ 9 2. User Requirements............................................................................................................ 11 2.1 Sources of Information and Definitions
    [Show full text]
  • Neural Networks Algorithms for the Estimation of Atmospheric Ozone from Envisat-SCIAMACHY and Aura-OMI Measurements
    TOR VERGATA UNIVERSITY, ROME, ITALY Department of Computer, Systems and Industrial Engineering GeoInformation PhD Programme XXI Cycle Neural Networks algorithms for the estimation of atmospheric ozone from Envisat-SCIAMACHY and Aura-OMI measurements A thesis submitted in partial fulfillment for the degree of Doctor of Philosophy Mentor: Fabio Del Frate Candidate: Pasquale Sellitto February 2009 Dedicated to Chiara i \Nature - the Gentlest Mother is Impatient of no Child - The feeblest - or the waywardest - Her Admonition mild - In Forest - and the Hill - By Traveller - be heard - Restraining Rampant Squirrel - Or too impetuous Bird - How fair Her Conversation - A Summer Afternoon - Her Household - Her Assembly - And when the Sun go down - Her Voice among the Aisles Incite the timid prayer Of the minutest Cricket - The most unworthy Flower - When all the Children sleep - She turns as long away As will suffice to light Her lamps - Then bending from the Sky - With infinite Affection - And infiniter Care - Her Golden finger on Her lip - Wills Silence - Everywhere -" Emily Dickinson Acknowledgements Nel settembre 2005, da neolaureato in Fisica all'Universit`a\La Sapienza", decisi di partecipare all'esame di ammisione al corso di Dottorato di Ricerca in GeoInformazione, all'Universit`a\Tor Vergata", Dipartimento di Ingegneria dell'Informazione. Oggi posso ammetterlo, avevo letto, in fretta e furia solo 2 o 3 articoli sul telerilevamento dell'atmosfera da satellite, li avevo letti rapidamente e non ci avevo capito molto. Ero vestito da “fisico", il che scaten´oqualche ilarit`a 1, e non conoscevo nessuno a Tor Vergata. Avevo alle spalle un contratto (che avevo rifiutato) da studente di dottorato al Forschungszentrum J¨ulich e la ragionevole prospettiva di vincere una posizione analoga per il dottorato in Teler- ilevamento a \La Sapienza".
    [Show full text]
  • SCIAMACHY V8 Solar Spectral Irradiance Validation
    SCIAMACHY V8 Solar Irradiance Validation scilov15_report_solar_V2.tex Version 2.0, 27-11-2017 Page 1 of 17 SCIAMACHY V8 Solar Spectral Irradiance Validation Tina Hilbig, Mark Weber, Klaus Bramstedt and John P. Burrows Institut für Umweltphysik, Universität Bremen, Bremen, Germany Document Number : scilov15_report_solar_V2.tex Version : 2.0 Date : November 27, 2017 Contact : Mark Weber ([email protected]) Universität Bremen FB1 P.O. Box 330 440 D-28334 Bremen Status : final ESA SCILOV-15 Project Technical Note SCIAMACHY V8 Solar Irradiance Validation scilov15_report_solar_V2.tex Version 2.0, 27-11-2017 Page 2 of 17 Contents 1 Introduction . 3 2 Solar Spectral Irradiance . 3 2.1 Instrument . 3 2.2 Solar Measurements . 4 3 Comparison of different Data Product Versions . 5 3.1 Version History . 5 3.2 Solar Mean Reference Spectrum . 6 3.3 Time Series . 8 4 Comparison with other Solar Reference Spectra . 11 5 Conclusions & Outlook . 13 6 References . 15 ESA SCILOV-15 Project Technical Note SCIAMACHY V8 Solar Irradiance Validation scilov15_report_solar_V2.tex Version 2.0, 27-11-2017 Page 3 of 17 1 Introduction SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) aboard the ESA Envisat satellite platform provided atmospheric trace gas measurements on a global scale for nearly a decade from August 2002 to April 2012 (Burrows et al., 1995; Bovensmann et al., 2011, and references therein). The trace gas retrievals are based upon Sun-normalized radiances, which are limb or nadir radiances divided by the solar irradiance. SCIAMACHY observes, therefore, the Sun directly once a day. Like other UV satellite sounders, the SCIAMACHY spectrometer suffers from optical degradation due to polymerisation of optical surfaces from the harsh UV radiation in space (e.g.
    [Show full text]
  • Evaluating a New Homogeneous Total Ozone Climate Data Record from GOME/ERS-2, SCIAMACHY/Envisat and GOME-2/Metop-A M
    Evaluating a new homogeneous total ozone climate data record from GOME/ERS-2, SCIAMACHY/Envisat and GOME-2/MetOp-A M. E. Koukouli, Christophe Lerot, José Granville, Florence Goutail, Jean-Christopher Lambert, Jean-Pierre Pommereau, D. Balis, I. Zyrichidou, Michel van Roozendael, M. Coldewey-Egbers, et al. To cite this version: M. E. Koukouli, Christophe Lerot, José Granville, Florence Goutail, Jean-Christopher Lambert, et al.. Evaluating a new homogeneous total ozone climate data record from GOME/ERS-2, SCIA- MACHY/Envisat and GOME-2/MetOp-A. Journal of Geophysical Research: Atmospheres, American Geophysical Union, 2015, 120 (23), pp.12296-12312. 10.1002/2015JD023699. insu-01240107 HAL Id: insu-01240107 https://hal-insu.archives-ouvertes.fr/insu-01240107 Submitted on 31 Aug 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. PUBLICATIONS Journal of Geophysical Research: Atmospheres RESEARCH ARTICLE Evaluating a new homogeneous total ozone climate data 10.1002/2015JD023699 record from GOME/ERS-2, SCIAMACHY/Envisat, Key Points: and GOME-2/MetOp-A • Validation of Ozone-CCI total ozone products from GOME/ERS-2, M. E. Koukouli1, C. Lerot2, J. Granville2, F. Goutail3, J.-C.
    [Show full text]
  • Intercomparison of Ground- and Satellite-Based Total Ozone Data Products at Marambio Base, Antarctic Peninsula Region
    atmosphere Article Intercomparison of Ground- and Satellite-Based Total Ozone Data Products at Marambio Base, Antarctic Peninsula Region Klára Cˇ ížková 1,2,*, Kamil Láska 1 , Ladislav Metelka 2 and Martin Stanˇek 2 1 Department of Geography, Faculty of Science, Masaryk University, 611 37 Brno, Czech Republic; [email protected] 2 Solar and Ozone Observatory, Czech Hydrometeorological Institute, 500 08 Hradec Králové, Czech Republic; [email protected] (L.M.); [email protected] (M.S.) * Correspondence: [email protected] Received: 26 October 2019; Accepted: 15 November 2019; Published: 18 November 2019 Abstract: This study aims to compare the ground-based Brewer spectrophotometer total ozone column measurements with the Dobson spectrophotometer and various satellite overpass data available at Marambio Base during the period 2011–2013. This station provides a unique opportunity to study ozone variability near the edge of the southern polar vortex; therefore, many institutions, such as the National Meteorological Service of Argentina, the Finnish Meteorological Institute and the Czech Hydrometeorological Institute, have been carrying out various scientific activities there. The intercomparison was performed using total ozone column data sets retrieved from the ground-based instruments and from Ozone Monitoring Instrument (OMI)—Total Ozone Mapping Spectrometer (TOMS), OMI–Differential Optical Absorption Spectroscopy (DOAS), Global Ozone Monitoring Experiment 2 (GOME2), and Scanning Imaging Absorption Spectrophotometer for Atmospheric Cartography (SCIAMACHY) satellite observations. To assess the quality of the selected data products, comparisons with reference to the Brewer spectrophotometer single observations were made. The performance of the satellite observational techniques was assessed against the solar zenith angle and effective temperature, as well as against the actual shape of the vertical ozone profiles, which represent an important input parameter for the satellite ozone retrievals.
    [Show full text]
  • SCIAMACHY: Mission Objectives and Measurement Modes
    VOL. 56, NO.2 JOURNAL OF THE ATMOSPHERIC SCIENCES 15 JANUARY 1999 SCIAMACHY: Mission Objectives and Measurement Modes H. BOVENSMANN,J.P.BURROWS,M.BUCHWITZ,J.FRERICK,S.NOEÈ L, AND V. V. R OZANOV Institute of Environmental Physics, University of Bremen, Bremen, Germany K. V. CHANCE Harvard±Smithsonian Center for Astrophysics, Cambridge, Massachusetts A. P. H. GOEDE SRON Ruimetonderzoek, Utrecht, the Netherlands (Manuscript received 5 September 1997, in ®nal form 16 June 1998) ABSTRACT SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) is a spectrometer designed to measure sunlight transmitted, re¯ected, and scattered by the earth's atmosphere or surface in the ultraviolet, visible, and near-infrared wavelength region (240±2380 nm) at moderate spectral resolution (0.2± 1.5 nm, l/Dl ø 1000±10 000). SCIAMACHY will measure the earthshine radiance in limb and nadir viewing geometries and solar or lunar light transmitted through the atmosphere observed in occultation. The extraterrestrial solar irradiance and lunar radiance will be determined from observations of the sun and the moon above the atmosphere. The absorption, re¯ection, and scattering behavior of the atmosphere and the earth's surface is determined from comparison of earthshine radiance and solar irradiance. Inversion of the ratio of earthshine radiance and solar irradiance yields information about the amounts and distribution of important atmospheric constituents and the spectral re¯ectance (or albedo) of the earth's surface. SCIAMACHY was conceived to improve our knowledge and understanding of a variety of issues of importance for the chemistry and physics of the earth's atmosphere (troposphere, stratosphere, and mesosphere) and potential changes resulting from either increasing anthropogenic activity or the variability of natural phenomena.
    [Show full text]
  • SCIAMACHY - Exploring the Changing Earth’S Atmosphere
    springer.com Manfred Gottwald, Heinrich Bovensmann (Eds.) SCIAMACHY - Exploring the Changing Earth’s Atmosphere provides a complete description of an Earth Observation mission from requirements to results provides a comprehensive summary of the results of a state-of-the-art atmospheric remote sensing enterprise links instrument design and data retrieval for atmospheric absorption spectroscopy links actual measurements to current discussions about global change SCIAMACHY, the SCanning Imaging Absorption spectroMeter for Atmospheric CHar•tographY, is a passive sensor for exploring the Earth’s atmosphere. It is part of the payload of the European Earth Observation mission ENVISAT, launched on 1 March 2002. SCIAMACHY 2011, XVI, 225 p. observes absorption spectra of molecules from the UV (214 nm) to the short-wave infrared wavelength range (2386 nm) and derives the atmospheric composition – trace gases, aerosols, Printed book clouds – from these measurements. Having meanwhile successfully monitored and explored the Earth’s atmosphere for more than 8 years, new and exciting insights into the Earth- Hardcover atmosphere system are obtained. The provided global data sets do not only cover greenhouse 149,52 € | £119.99 | $179.99 gases and pollutants in the troposphere or the ozone chemistry in the stratosphere but even [1]159,99 € (D) | 164,47 € (A) | CHF reach up to the mesosphere and lower thermosphere. They contribute significantly to 176,50 atmospheric physics and chemistry as well as climate change research. SCIAMACHY is one of Softcover the major current Earth Observation undertakings of Germany, The Netherlands and Belgium, 130,83 € | £99.99 | $149.99 accomplished in cooperation with the European Space Agency (ESA).
    [Show full text]
  • Composition and Chemistry of the Neutral Atmosphere of Venus Emmanuel Marcq, Franklin P
    Composition and Chemistry of the Neutral Atmosphere of Venus Emmanuel Marcq, Franklin P. Mills, Christopher D. Parkinson, Ann Carine Vandaele To cite this version: Emmanuel Marcq, Franklin P. Mills, Christopher D. Parkinson, Ann Carine Vandaele. Composition and Chemistry of the Neutral Atmosphere of Venus. Space Science Reviews, Springer Verlag, 2018, 214, pp.article 10. 10.1007/s11214-017-0438-5. insu-01656562 HAL Id: insu-01656562 https://hal-insu.archives-ouvertes.fr/insu-01656562 Submitted on 6 Dec 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Composition and Chemistry of the Neutral Atmosphere of Venus Emmanuel Marcq1 · Franklin P. Mills2 · Christopher D. Parkinson3 · Ann Carine Vandaele4 E. Marcq [email protected] 1 LATMOS/Université de Versailles Saint-Quentin, Guyancourt, France 2 Australian National University, Canberra, Australia 3 University of Michigan, Ann Arbor, USA 4 Belgian Institute for Space Aeronomy, Uccle, Belgium Abstract This paper deals with the composition and chemical processes occurring in the neutral atmosphere of Venus. Since the last synthesis, observers as well as modellers have emphasised the spatial and temporal variability of minor species, going beyond a static and uniform picture that may have prevailed in the past.
    [Show full text]
  • Atmospheric Absorption Atmospheric Absorption
    Atmospheric Absorption Atmospheric Absorption The energy structure of atoms and molecules is composed of discrete energy levels. Energy levels are said to be quantised. Photons of electromagnetic radiation also have discrete energy, which is proportional to frequency via Plancks constant, h. Thus E = hf where f is the frequency. A photon with a frequency such that E1 - E0 = hf0 (where E1 and E0 correspond to a possible transition within the molecule) will be absorbed (as illustrated below) subject to probability whereas no other frequency will interact with the molecule; at least for this energy transition. As a result some energy will be removed from the photon field at exactly the frequency f0 and thus a spectral line will be observed at this frequency. Transitions can be electronic, vibrational or rotational. The energy levels involved for the different types of transition are generally well separated so that Eel > Evib > Erot. Rotational features in the spectrum typically occur in the far infrared. Vibrational features occur in the mid and near infrared whereas electronic transitions are mainly located in the UV and visible regions. For a given molecule, the contribution of the different possible transitions combined with different broadening effects results in complex absorption features as a function of wavelength. As an example, the graph below shows the absorption cross section of Ozone in the Higgins Bands (UV) for two different temperatures. http://envisat.estec.esa.nl/support-docs/atmospheric-absorption/atmospheric-absorption.html (1 of 3) [5/24/1999 11:50:14 AM] Atmospheric Absorption The actual shape of the aborption features and the wavelength regions where aborptions occur are different for each molecule.
    [Show full text]
  • Validation of SCIAMACHY HDO/H2O Measurements Using the TCCON and NDACC-MUSICA Networks
    Atmos. Meas. Tech., 8, 1799–1818, 2015 www.atmos-meas-tech.net/8/1799/2015/ doi:10.5194/amt-8-1799-2015 © Author(s) 2015. CC Attribution 3.0 License. Validation of SCIAMACHY HDO=H2O measurements using the TCCON and NDACC-MUSICA networks R. A. Scheepmaker1, C. Frankenberg2, N. M. Deutscher3,4, M. Schneider5,6, S. Barthlott5, T. Blumenstock5, O. E. Garcia6, F. Hase5, N. Jones4, E. Mahieu7, J. Notholt3, V. Velazco4, J. Landgraf1, and I. Aben1 1SRON Netherlands Institute for Space Research, Utrecht, the Netherlands 2Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA, USA 3Institute for Environmental Physics, University of Bremen, Bremen, Germany 4Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, Australia 5Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany 6Izaña Atmospheric Research Centre (IARC), Agencia Estatal de Meteorología (AEMET), Santa Cruz de Tenerife, Spain 7Institute of Astrophysics and Geophysics, University of Liège, Liège, Belgium Correspondence to: R. A. Scheepmaker ([email protected]) Received: 20 October 2014 – Published in Atmos. Meas. Tech. Discuss.: 27 November 2014 Revised: 26 March 2015 – Accepted: 27 March 2015 – Published: 21 April 2015 Abstract. Measurements of the atmospheric HDO=H2O ra- ments nor to a strong reduction of the latitudinal dependency tio help us to better understand the hydrological cycle and of the bias. The correction might be an improvement for dry, improve models to correctly simulate tropospheric humid- high-altitude areas, such as the Tibetan Plateau and the An- ity and therefore climate change. We present an updated ver- des region. For these areas, however, validation is currently sion of the column-averaged HDO=H2O ratio data set from impossible due to a lack of ground stations.
    [Show full text]
  • Atmospheric Greenhouse Gases Retrieved from SCIAMACHY: Comparison to Ground-Based FTS Measurements and Model Results
    Atmos. Chem. Phys., 12, 1527–1540, 2012 www.atmos-chem-phys.net/12/1527/2012/ Atmospheric doi:10.5194/acp-12-1527-2012 Chemistry © Author(s) 2012. CC Attribution 3.0 License. and Physics Atmospheric greenhouse gases retrieved from SCIAMACHY: comparison to ground-based FTS measurements and model results O. Schneising1, P. Bergamaschi2, H. Bovensmann1, M. Buchwitz1, J. P. Burrows1, N. M. Deutscher1,3, D. W. T. Griffith3, J. Heymann1, R. Macatangay3, J. Messerschmidt4, J. Notholt1, M. Rettinger5, M. Reuter1, R. Sussmann5, V. A. Velazco1, T. Warneke1, P. O. Wennberg4, and D. Wunch4 1Institute of Environmental Physics (IUP), University of Bremen FB1, Bremen, Germany 2Institute for Environment and Sustainability (IES), European Commission Joint Research Centre (EC-JRC), Ispra, Italy 3School of Chemistry, University of Wollongong, Wollongong, New South Wales, Australia 4California Institute of Technology, Pasadena, California, USA 5Institute for Meteorology and Climate Research (IMK-IFU), Garmisch-Partenkirchen, Germany Correspondence to: O. Schneising ([email protected]) Received: 18 September 2011 – Published in Atmos. Chem. Phys. Discuss.: 26 October 2011 Revised: 27 January 2012 – Accepted: 30 January 2012 – Published: 9 February 2012 Abstract. SCIAMACHY onboard ENVISAT (launched in cribed to occurrences of undetected thin clouds. Based on 2002) enables the retrieval of global long-term column- the comparison with the reference data, we conclude that the averaged dry air mole fractions of the two most important carbon dioxide data set can be characterised by a regional rel- anthropogenic greenhouse gases carbon dioxide and methane ative precision (mean standard deviation of the differences) (denoted XCO2 and XCH4). In order to assess the quality of about 2.2 ppm and a relative accuracy (standard deviation of the greenhouse gas data obtained with the recently intro- of the mean differences) of 1.1–1.2 ppm for monthly average duced v2 of the scientific retrieval algorithm WFM-DOAS, composites within a radius of 500 km.
    [Show full text]
  • Analysis of MESSENGER/MASCS Data During Second Venus Flyby
    EPSC Abstracts Vol. 8, EPSC2013-156, 2013 European Planetary Science Congress 2013 EEuropeaPn PlanetarSy Science CCongress c Author(s) 2013 Analysis of MESSENGER/MASCS data during second Venus flyby S. Pérez-Hoyos (1), A. García-Muñoz (2), A. Sánchez-Lavega (1), G. Holsclaw (3) and W.M. McClintock (3) (1) Dpto. Física Aplicada I, ETS Ingeniería UPV/EHU, Bilbao, Spain, (2) ESA/RSSD, ESTEC, The Netherlands, (3) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA, ([email protected] / Fax: +34- 94-6014178) Abstract band in UVVIS detector and both the VIS and NIR bands in the VIRS spectrograph. In June 2007, the MESSENGER spacecraft performed its second Venus flyby during its travel to 2. Data analysis Mercury. The spacecraft acquired several spectra of the reflected sunlight from the equatorial region of Radiance measurements obtained were tranformed the planet and covering from the middle ultraviolet into absolute reflectivity (I/F). Since our radiative (195nm) to the near infrared (1450 nm) using the transfer codes are restricted to work under the plane- MASCS instrument (MUV-UVVS and VIRS parallel approximation, we restricted the 960 channels). In this work we present an analysis of the available spectra (VIRS channels) to 318 usable data and their spectral and spatial variability spectra with moderate values for the following the mission footprint on the Venus disk. In illumination/observation angles. Those spectra were order to reproduce the observed reflectivity and acquired at latitudes located in the band from the obtain information on the upper clouds and the Equator to 10º S while the spacecraft footprint moved unknown UV absorber, we use XtraRT, a radiative from the limb of the planet close to the sub-solar transfer code based on DISORT and the HITRAN point to the terminator and close to the sub-observer database, which includes SO, SO2, CO2 and H2O absorption together with absorption and scattering by mode-1 and mode-2 cloud particles.
    [Show full text]