Geophysical validation of NSCAT winds using atmospheric data and analyses

A detailed geophysical evaluation of the initial NASA scatterometer (NSCAT) wind data sets was performed in order to determine the error characteristi cs of these data and their applicability to ocean surface analysis and nume rical prediction. The first component of this evaluation consisted of collo cations of NSCAT data to ship and buoy wind reports, special sensor microwa ve imager wind observations, and National Centers for Environmental Predict ion and Goddard Earth Observing System (GEOS) model wind analyses. This was followed by data assimilation experiments to determine the impact of NSCAT data on analysis and forecasting. The collocation comparisons showed the N SCAT wind velocity data to be of higher accuracy than operational ERS 2 win d data. The impact experiments showed that NSCAT has the ability to correct major errors in analyses over the oceans and also to improve numerical wea ther prediction. NSCAT data typically show the precise locations of both sy noptic-scale and smaller-scale cyclones and fronts over the oceans. This of ten results in significant improvements to analyses. Forecast experiments u sing the GEOS model show approximately a 1-day extension of useful forecast skill in the southern hemisphere, in good agreement with the results of Ob serving System Simulation Experiments conducted prior to launch.