A COMPARISON OF SURFACE WIND PRODUCTS OVER THE NORTH PACIFIC-OCEAN

This study compares four surface wind products which may be used to fo rce ocean circulation models of the North Pacific: wind stress derived from the Atlas special sensor microwave imager (SSM/I) based surface wind analyses (July 1987-June 1990), the Goddard Earth Observing Syste m (CEOS) wind assimilation product at 10 m (March 1985-February 1990) and, at the appropriate overlapping times, the European Centre for Med ium-Range Weather Forecasts (ECMWF) wind analyses and the Comprehensiv e Ocean-Atmosphere Data Set (COADS). Overall, there is good agreement in spatial and temporal variations between COADS and the model-based a nalyses. The COADS product used in this study, based on monthly averag ed winds, underestimates the monthly averaged stresses in the higher l atitudes where the submonthly variance is high. In the tropics and sub tropics where the variance is lower, the COADS stresses are closer to climatology than the weaker model-based winds. The largest differences between the model-based analyses occur during winter in the northernm ost region of the North Pacific basin where the spatial and temporal v ariability is largest. The seasonal mean Atlas SSM/I stresses are stro nger overall than the other model-based analyses, with differences rea ching as high as 0.09 N m(-2) in the high latitudes during winter. The Atlas product is also consistently stronger in the curl. Of the four curl products, the Atlas SSM/I and GEOS are closest in pattern and int ensity in the tropics in both summer and winter. These also have the c losest wavenumber spectral distribution in the high latitudes during w inter. Integrations of a nonlinear, baroclinic quasigeostrophic ocean model using three of the wind stress curl distributions show differenc es of 30-45% in the mean integrated volume transport in the Kuroshio E xtension. The Atlas SSM/I wind stress curl seems to force a more reali stic subtropical gyre (in terms of transport and eddy energy levels) a nd western boundary current structure. The GEOS curl seems to force a more realistic subpolar gyre circulation. Overall, the assimilation of the SSM/I wind speed data improves the comparison between the model-b ased analyses and ship-based observations and produces more a realisti c ocean model circulation.