A new source of vector wind stress data is assessed relative to existing analyses of the surface wind field. The large-scale variability of vector wind stress generated by Atlas et al. (1991) and based on the special sensor microwave imager (SSM/I) remotely sensed observations of surface wind speed is compared with five operational and subjectively analyzed wind products across the tropical Pacific basin for the first year of SSM/I, July 1987 through June 1988. The conventional wind stress data considered are the operational wind products from European Centre for Medium Range Weather Forecasts (ECMWF), National Meteorological Center (NMC), and Fleet Numerical Oceanography Center (FNOC), and the subjective analyses from Florida State University and the University of Hawaii. The spatial and temporal variability of the zonal component, meridional component, and curl of the wind stress are examined relative to their future use in wind-driven ocean model studies of tropical Pacific Ocean circulation. The basin-scale structure of SSM/I data fall within a range bracketed by ECMWF, the University of Hawaii, NCM, and the Florida State products. The SSM/I data are shown to be most similar to the ECMWF analysis and the subjective analysis of satellite-derived cloud motion wind vectors (SAWIN) performed at the University of Hawaii.

The basin-wide mean rms difference between the SSM/I data and these two products is 0.18 dyn cm-2 for &tgr;x and 0.10--0.12 dyn cm-2 for &tgr;y. In order to place these differences within context, the basin-wide mean standard deviation for the temporal variability is found to be 0.23--0.26 dyn cm-2 for &tgr;x and 0.15--0.16 dyn cm-2 for &tgr;y. On regional scales, some of the differences among these products are greater than 0.3 dyn cm-2. The ECMWF and SAWIN analyses are the most similar (basin-wide mean rms difference &tgr;x=0.16 dyn cm-2, &tgr;y=0.11 dyn cm-2) of the 15 possible product versus product comparisons. This may indicate a high weight given to cloud motion wind vectors in the ECMWF analysis for data sparse regions of the tropical Pacific. The wind data from the FNOC analysis forecast system in use in 1987--1988 (and since upgraded) was the most dissimilar wind product. The relatively dense space-time coverage of the SSM/I satellite data (order of 27 observations per 2¿¿2.5¿ grid square every1.5 days), together with the large-scale similarity with conventional wind products, suggests that the SSM/I-based analysis represents a new source of surface wind information suitable for ocean modeling studies. As a result of the potential demonstrated here, strong consideration should be given to the use of these wind data in forcing ocean circulation modeling studies. Furthermore, the prospects of processing the surface wind speed retrievals from spaceborne passive and active microwave sensors dating back for more than 10 years should be examined. ¿ American Geophysical Union 1993