Test of the MIPAS retrieval code with ATMOS measurements

The Optimized Retrieval Model (ORM), developed for the level-2 analysis of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment, is tested using spectra measured by atmospheric trace molecule spectroscopy (ATMOS). The ORM can analyze simultaneously a large number of spectra and perform statistical analysis of the residuals. This approach enables the inference of some instrumental effects and identifies the most important sources of systematic errors. This is not generally considered in level 2 analyses. The objectives of this study are the validation of the ORM with real data and use of the level 2 analysis as a diagnostic tool. Information on data processing, instrument characterization, and spectroscopy is obtained through sensitivity tests. The approach used here is to simulate with a parameter the possible instrument effects as a part of the forward model calculation and select for this parameter the value that minimizes the x test. Comparisons between retrieved profiles before and after this optimization procedure confirm that the original characterization of ATMOS measurements is generally very good. The good agreement between ORM and Jet Propulsion Laboratory (JPL) profiles provides a validation of the performances of the ORM scheme.