Mapping of temperature and Line-of-Sight Errors in Constituent retrievals for MIPAS / ENVISAT Measurements

An optimized code for the near real-time retrieval of line of sights, temperature and volume mixing ratio profiles of five key species (O3, H2O, HNO3, CH4 and N2O) from infrared limb spectra recorded by the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) experiment on board the ENVISAT-1 satellite was developed as part of an ESA-supported study. In this code line of sight and temperature are retrieved simultaneously among themselves, but sequentially with respect to the volume mixing ratio of the five key species. The sequential retrieval leaves unaccounted the mapping of line of sight and temperature errors in the retrieved volume mixing ratio of the constituents. This paper illustrates an algorithm that provides the a- posteriori evaluation of temperature and line-of-sight induced error on the retrieved volume mixing ratio of the MIPAS key species. It is shown that in most cases temperature and line-of-sight induced error provides a significant contribution to the total volume mixing ratio error. The variability of this error as a function of latitude, season and atmospheric model is also analyzed. Keywords: Chemistry of the atmosphere, remote sensing, FTIR spectroscopy measurements, inversion techniques, error assessment