An investigation into the performance of retrievals of temperature and humidity from IASI

The meteorological community has had access to operational data from the Infrared Atmospheric Sounding Interferometer (IASI) since July 2007. The data are now successfully assimilated at many operational meteorological centres, which have demonstrated good impact on forecast skill from the use of the data for temperature and humidity sounding. The next stage in increasing the impact from IASI data is to understand the limitations of our processing methodology, and thus determine where modifications to processing or further research could enable us to extract more information from IASI. One way of investigating where the limitations of a particular methodology might be is to perform a careful intercomparison of the results of different retrieval schemes for the same observations. For this study, nine different retrieval schemes are applied to twenty five clear sky cases which form part of the Joint Airborne IASI Validation Experiment (JAIVEx) campaign of April-May 2007. The resulting retrievals are verified using near-coincident dropsonde data collected during the campaign. It is hoped that the similarities and differences in the retrievals from the different schemes shown here will guide future research into the best methods of using IASI data.