Influence of the Error Covariance structure on satellite-derived atmospheric winds over the southern oceans

Zou and Van Woert (2002) developed a technique that uses a Special Sensor Microwave/Imager (SSM/I) -based surface wind and the Television and Infrared Observational Satellite (TIROS) Operational Vertical Sounder (TOVS) temperature soundings for deriving three-dimensional atmospheric wind fields over the middle- and high-latitude oceans. In this work we use the NESDIS AMSU (Advanced Microwave Sounding Unit) temperature retrievals (Goldberg et al. 2000) to replace the TOVS soundings to retrieve the atmospheric wind. AMSU-A is the first of a new generation of polar–orbiting cross-track microwave sounders operated by the National Ocean and Atmospheric Administration. A similar variational procedure to that of Zou and Van Woert is used to force the first-guess, nonmass-conserved atmospheric wind (Slonaker and Van Woert 1999) to conserve mass. All data have spatial resolution of 1 degree latitude by 1 degree longitude. Preliminary results show that the case of Zou and Van Woert produces reasonable atmospheric wind compared to the observations and ECMWF (European Center for Medium-Range Weather Forecasts) re-analysis. However other cases may improve the retrievals further. Full results will be presented at the conference.