Recent developments in the use of ATOVS data at ECMWF

Early 2007 saw the operational use of ATOVS data from METOP-A, Europe's first operational polar- orbiting weather satellite, launched 19 October 2006. Operational monitoring of the first ATOVS data from METOP-A at ECMWF commenced two weeks after launch, and the quality of AMSU-A and MHS data was found comparable to that of similar instruments on the NOAA satellites. Assimilation trials show a positive forecast impact over the Southern Hemisphere. Similarly, data from the HIRS instrument showed expected quality, and adding the METOP-A HIRS instrument to the assimilation system results in a more neutral forecast impact. Other recent developments include work towards the improved use of surface-sensitive microwave data over land in the ECMWF system. Experiments have been performed with methods recently developed at Météo France, based on a dynamic retrieval of surface emissivity from window channels and FG information. Applying this approach to data from AMSU-A and AMSU-B/MHS leads to smaller First Guess departures for surface-sensitive channels over land, and small positive forecast impact over both hemispheres. Bias correction and quality control require further attention.