The impact of ATOVS on NWP

The accuracy of NWP has improved very significantly in recent years. Satellite data has been a major contributor to this improvement and of the various satellite data available to NWP centres ATOVS is found, at present, to have the largest impact. It is generally accepted that it is the microwave data which supplies much of the impact of ATOVS. However the infrared components, and for that matter other satellite data types still have an important role to play in specific situations (e.g. tropical storms).

SH pmsl T+72
This figure shows the improvement in NWP since 1997 as a yearly average of RMS error of 250 hPa wind for the southern hemisphere verified against radiosondes at T+72. Most NWP centres who made effective early use of ATOVS have seen substantial reduction in forecast RMS error since 1998. The reductions in error are similar for all centres ranging from 30% to 40% with the largest falls being for those centres using radiances from ATOVS. There are similar falls for almost all meteorological variables for which verification is exchanged under CBS (commission for basic systems) rules. Combined with evidence from trials (e.g. English et al. 2000, QJ Royal Meteorol. Soc. 126 (569): 2911-2931) it is generally accepted that ATOVS data has been an important factor in the large improvements seen in recent years.

To find out more the ITSC proceedings are a vital source of information. Regular progress reports and reports on OSEs are provided by met services. For results of OSEs including satellite data OSEs the WMO OSE workshop proceedings are a useful source of information. There was also an important workshop at ECMWF in 1999 (A.P. McNally. ECMWF/EUMETSAT Workshop on Use of ATOVS Data for NWP Assimilation, 2-5 November 1999, Shinfield Park, Reading, 1999.)

A number of papers have been written on the impact of ATOVS on NWP. A selection are given below. Click on titles for abstracts and full reference details.