ASSIMILATION EXPERIMENTS WITH DATA FROM THREE CONICALLY SCANNING MICROWAVE INSTRUMENTS (SSMIS, AMSR-E, TMI) IN THE ECMWF SYSTEM

The status of monitoring and assimilation experiments with clear-sky radiances from SSMIS, AMSR-E, and TMI is presented. SSMIS combines channels similar to AMSU-A, AMSU-B, and SSMI, with a three-channel mesospheric sounder in one conically scanning instrument, whereas AMSR-E and TMI are microwave imagers similar to SSMI. The quality of the data is assessed by comparisons against model equivalents. For SSMIS, the pre-processed dataset prepared by the Met.Office is used. Window channels on SSMIS, AMSR-E, and TMI primarily provide information on total column water vapour, and monitoring of the radiance data indicates a quality that is comparable to that of SSMI. Assimilation trials with data from these instruments show a positive forecast impact for lower tropospheric humidity and surface wind in the tropics. Monitoring of the temperature-sounding channels of the F-16 SSMIS shows that noise characteristics for the pre-processed data approach those of AMSU-A, but considerable local biases remain. Assimilation trials show a neutral impact of the SSMIS temperature-sounding channels from adding these channels to the full operational set of observations. However, when added to a system that otherwise makes limited use of satellite data, SSMIS can lead to improved forecasts.