One of the important applications of satellite surface wind observations is to increase the accuracy of weather analyses and forecasts. Satellite surface wind data can improve numerical weather prediction (NWP) model forecasts by contributing to improved analyses of the surface wind field and air sea fluxes. Through the data assimilation process,these data can also improve atmospheric mass and motion fields in the free atmosphere above the surface. SeaWinds scatterometer data are available from both the QuikScat and ADEOS 2 satellites. SeaWinds (like NSCAT and ERS) is able to detect unequivocal signatures of meteorological features including cyclones, fronts, anticyclones, easterly waves and other precursors of hurricanes and typhoons.The NASA Goddard Laboratory for Atmospheres has been assimilating Quikscat data since 1999 and are currently evaluating the quality of the ADEOS 2 data and its potential to improve atmospheric analyses and forecasts. At the conference we will present detailed results from this evaluation, as well as the impact of each of the scatterometers on data assimilation and numerical weather prediction.