Intercomparison of ILAS-II version 1.4 and version 2 target parameters with MIPAS-Envisat measurements
This paper assesses the mean differences between the two ILAS-II data versions (1.4 and 2) by comparing them with MIPAS measurements made between May and October 2003. For comparison with ILAS-II results, MIPAS data processed at the Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany (I...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2008-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/8/825/2008/acp-8-825-2008.pdf |
| Summary: | This paper assesses the mean differences between the two ILAS-II data versions (1.4 and 2) by comparing them with MIPAS measurements made between May and October 2003. For comparison with ILAS-II results, MIPAS data processed at the Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany (IMK) in cooperation with the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain, were used. The coincidence criteria of &plusmn;300 km in space and &plusmn;12 h in time for H<sub>2</sub>O, N<sub>2</sub>O, and CH<sub>4</sub> and the coincidence criteria of &plusmn;300 km in space and &plusmn;6 h in time for ClONO<sub>2</sub>, O<sub>3</sub>, and HNO<sub>3</sub> were used. The ILAS-II data were separated into sunrise (= Northern Hemisphere) and sunset (= Southern Hemisphere). For the sunrise data, a clear improvement from version 1.4 to version 2 was observed for H<sub>2</sub>O, CH<sub>4</sub>, ClONO<sub>2</sub>, and O<sub>3</sub>. In particular, the ILAS-II version 1.4 mixing ratios of H<sub>2</sub>O and CH<sub>4</sub> were unrealistically small, and those of ClONO<sub>2</sub> above altitudes of 30 km unrealistically large. For N<sub>2</sub>O and HNO<sub>3</sub>, there were no large differences between the two versions. Contrary to the Northern Hemisphere, where some exceptional profiles deviated significantly from known climatology, no such outlying profiles were found in the Southern Hemisphere for both versions. Generally, the ILAS-II version 2 data were in better agreement with the MIPAS data than the version 1.4, and are recommended for quantitative analysis in the stratosphere. For H<sub>2</sub>O data in the Southern Hemisphere, further data quality evaluation is necessary. |
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| ISSN: | 1680-7316 1680-7324 |