Anu Dudhia

Abstract:

There are two level 2 data resources provided by ESA for MIPAS users. These are the Near Real Time (NRT) and Offline data sets. We investigate the differences observed between these products over a large number of profiles, to assist in validating their mutual consistency and determining the effect of the differing data processing routes.

Abstract:

Monthly mean profiles have been calculated for the MIPAS Near-Real-Time Level 2 products (temperature, H2O, O3, HNO3, CH4, N2O and NO2) from July 2002 until March 2004. The Level 2 profiles have been split into six latitude bands (90S-65S, 65S-20S, 20S-0, 0-20N, 20N-65N, 65N-90N) for the calculation of the means. Here we compare these monthly means with reference climatologies for each of the Level 2 products to provide an overview of the quality of these products over the timescale that MIPAS has been operating. The reference climatologies used in these comparisons are the COSPAR International Reference Atmosphere (CIRA) (2) for temperature and the IG2 dataset (1) (used in the construction of the initial guess for MIPAS retrievals) for the gases.

Abstract:

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a polar orbiting high resolution mid-infrared emission stratospheric limb sounder with a nominal vertical resolution of 3 km. Work to extend the list of interesting, routinely retrieved species led to the examination of SF6, a potent greenhouse gas and a useful tracer species. We demonstrate the feasibility of profile retrievals in the range 6-30 km based on single scans. Additionally, we investigate latitudinal variation using coaddition to improve signal-to-noise. A mean mid-latitude profile shows tropospheric (4.32 +/- 0.03 pptv, 6-12 km) and stratospheric (3.50 +/- 0.03 pptv, 21-30 km) regimes, in September 2002, similar to accepted values. The global mean contains an interhemispheric variability of the order of 0.3 pptv in the lower stratosphere, in line with age of air. Finally, the continuation of acknowledged global trends in atmospheric concentration, is estimated at +0.28 pptv yr(-1) (6.5 +/- 1.3% yr(-1)).

Abstract:

Michelson interferometer for passive atmospheric sounding (MIPAS) is operating on board of the ENVISAT satellite and is acquiring for the first time high spectral resolution middle infrared emission limb sounding spectra of the Earth atmosphere from space. An optimized code was developed for the Level 2 near real time analysis of MIPAS data. The code is designed to provide, in an automated and continuous way, atmospheric vertical profiles of temperature, pressure and concentrations of O-3, H2O, CH4, HNO3, N2O and NO2, in the altitude range from 12 to 68 km. The performances of the code are herewith derived from the analysis of the first measurements acquired with this instrument. The assumptions made for the development of the optimized code are verified with the real data. The diagnostics of the instrument performances provide indications that there is good agreements with the results obtained by the Level 1 analysis. Consistent geophysical data are retrieved which is a first step towards a more complete assessment of retrieval accuracy. The tests have identified the possibility of measurement improvements by way of some secondary operations such as a correction of the frequency scale and the use of cloud filtering. However, no change in the algorithm baseline appears to be necessary. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.