For years the use of satellite data has increased in the assimilation systems for numerical weather prediction models. Data from nadir viewing passive microwave sounders has mainly been used in the global assimilation systems. The use has also been increased to regional models, mainly due to the improved information extraction possible with varational assimilation schemes and the improved possibilities of near real time data access.
We describe the system implemented at the Danish Meteorological Institute for assimilating ATOVS AMSU-A data. Initially over open water and cloud free area due to the relative simple surface charactersitics. Currently the system is under development to include data usage over land and sea-ice. For this purpose we only use data from a reduced number of channels.
The original open water assimilation gave slight positive impact in the winter season and positive or neutral impact during summer season. The extended data usage over sea ice will increase the amount of used data significantly, and is expected to give further positive impact, most noticeable at high latitudes.