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Radiometric Calibration for SCIAMACHY Level-1 Validation using Balloonborne DOAS/LPMA Spectrometers

This study focuses on the radiometric calibration of balloonborne DOAS/LPMA spectrometers to validate SCIAMACHY Level-1 Products such as solar irradiance and radiance. The calibration lab has been set up with certified reference sources, and a method for measuring TOA solar irradiance using LPMA-DOAS in occultation is proposed. Additional sensors including airborne and ground-based DOAS are also used for radiance validation. Future activities involve the use of ground-based DOAS, airborne AMAXDOAS, and LPMA-DOAS balloon for LV-1 validation.

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Radiometric Calibration for SCIAMACHY Level-1 Validation using Balloonborne DOAS/LPMA Spectrometers

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  1. SCIAMACHY level-1 validation using radiometric calibration of balloonborne DOAS/LPMA spectrometers • Level-1 Products: • solar irradiance • (occultation geometry) • radiance (addition, nadir • geometry) • Cooperation: • LPMA Paris (C. Camy-Peyret) • -IUP Heidelberg (K. Pfeilsticker) • -IUP Heidelberg (T.Wagner) • -IUP Bremen (A. Richter)

  2. Progress: 1) Calibration Lab has been set up with 3 fully certified and characterized reference sources (NIST & PTB) 2) Campaign sources can be calibrated in-house Solar irradiance calibration source for balloonborne occultation instruments LPMA and DOAS (campaign use, 300-2400 nm) beam geometry optimized

  3. Method for measurement of TOA solar irradiance using balloonborne LPMA-DOAS in occultation 1- radiometric calibration of ballonborne sensors 2- measurements in occultation geometry at various solar elevation angles 3- calculation of airmass-factors 4- extrapolation of airmass-factors to AMF = 0 using Langley-plot method 5- result is TOA (extraterrestrial) solar irradiance

  4. 3) Additional sensors (nadir+zenith) : extended to airborne (AMAXDOAS) and ground-based (Bremen & Nairobi) DOAS for level-1 radiance validation (UV-VIS)

  5. Radiometric calibration before and after flight to Kiruna

  6. Method for radiance measurements -radiometric calibration of sensors, then measurement -modelling radiation transfer (SCIATRAN) -using measured aerosol and trace gas data for realistic model absolute radiance measurement (ground-based DOAS Bremen) illustration of method (preliminary result)

  7. Winter 2003 Kiruna Campaign: solar irradiance measurements using absolute calibration of LPMA / DOAS TOA solar irradiance calculated using Langley-Plot (example, historic data)

  8. Future Activities for LV-1 Validation • use of ground-based DOAS (zenith-sky) • -use of airborne AMAXDOAS (nadir + zenith) • -use of LPMA-DOAS balloon (occultation) • -option: use of mini-DOAS balloon (nadir) Calibration stability of ground-based and airborne DOAS 3%, improvements possible Calibration stability of balloonborne LPMA, DOAS, mini DOAS not yet known

  9. Sciamachy validation using H2O and CH4 profiles • obtained in-situ by ballon-borne TDL (tunable diode laser) measurements with the CHILD • compact • high-altitude • insitu • laser • diode • Spectrometer • Partners: • Univ. Heidelberg • -TRIPLE (Jülich: C. Schiller, • F. Stroh, Frankfurt A. Engel)

  10. CHILD measurement of water vapor and methane profiles on TRIPLE flight from Aire sur L´Adour, 24.09.2002, (descent), matched with SCIAMACHY overpass Temporal resolution: 1 sec. for averaged data (2-4 meters altitude resolution)

  11. TRIPLE-flight with CHILD from ASA on 24-SEP-2002 <overpass SCIAMACHY - match at the middle of descent (30-40 hPa)

  12. Future activities for the CHILD spectrometer ....continue missions with TRIPLE

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