Impact of NOAA16 and NOAA17 ATOVS AMSU-A radiance data in the DMI-HIRLAM 3D-VAR analysis and forecasting system - January and February 2003

This report describes relevant statistics for the satellite observations used and the results from an observing system experiment (OSE) using Advanced TIROS (Television Infra-Red Observation Satellite) Operational Vertical Sounder (ATOVS) brightness temperatures from the polar orbiting satellites NOAA16 and NOAA17 (National Oceanic and Atmospheric Administration) in near real-time in January and February 2003. The reference experiment does not use ATOVS data. All AMSU-A (Advanced Microwave Sounding Unit-A) level 1c data (channels 1 to 10, only) available from locally received data from the DMI Smidsbjerg antenna as well as from the DMI Sdr. Strømfjord/Kangerlussuaq (Greenland) antenna have been used. An example from November 2002 shows the importance of the first guess check. Based on observation (obs-) and field verification the impact is positive in this period.