On the accuracy of GOME and SCIAMACHY total ozone measurements in polar regions

Christophe Lerot, Michel Van Roozendael, Jos van Geffen,
Jeroen van Gent, Caroline Fayt, Robert Spurr
in: Proceedings of the 2007 ENVISAT Symposium, 23--27 April 2007
Montreux, Switzerland, ESA publication SP-636 (CD-ROM).

Abstract

Total ozone retrieval algorithms applied operationally to GOME and SCIAMACHY data have been based on the Differential Optical Absorption Spectroscopy (DOAS) technique for several years. These algorithms produce retrieval results within the 1% precision level in low- and mid-latitude regions. However, in polar regions, there are persistent discrepancies with respect to reference ground-based and complementary satellite data sets (e.g. from the TOMS instrument).

We use the Direct Fitting part of the GODFIT software to investigate these total ozone retrieval issues in the polar regions. Sensitivity tests show the influence on the ozone columns of key input parameters such as cloud parameters (FRESCO or OCRA-ROCINN), O3 climatology (TOMS v8 or DOC), surface albedo, and temperature profile data bases. The two SAUNA campaigns in Sodankylä (67° N, 26° E) provide good opportunities to validate our algorithm in polar regions. Based on these results, one expects a consolidation of the retrieved GOME and SCIAMACHY O3 columns in polar regions, even at high solar zenith angle.


contents

   Abstract
   1. Introduction
   2. The GODFIT algorithm
   3. The ozone cross-sections
   4. Sensitivity tests
      4.1  Temperature profile
      4.2  O3 profile climatology
      4.3  Cloud algorithm
      4.4  Surface albedo
   5. Conclusions
   Acknowledgments
   References

PDF file of the paper (6 pages; 472 kB)


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created: 7 May 2007
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