Evaluation of ocean surface vector winds observed by QuikSCAT/seawinds and ADEOS-II/seawind

Ocean surface vector winds observed by QuikSCAT/SeaWinds and ADEOS-II/SeaWinds are evaluated by comparison with wind and wave data from the NDBC (National Data Buoy Center), TAO (Tropical Atmosphere and Ocean)/TRITON (Triangle Trans-Ocean buoy Network), PIRATA (Pilot Research Moored Array in the Tropical Atlantic), and JMA (Japan Meteorological Agency) buoys in the Atlantic and Pacific Oceans, Gulf of Mexico, and seas around Japan. Only buoys located offshore and in deep water were analyzed. The temporal and spatial separations between the scatterometer and buoy observations were limited to less than 10 min and 12.5 km. The buoy wind speeds were converted to equivalent neutral winds at a height of 10 m above the sea surface. The comparisons show that the wind speeds and directions observed by the two Sea Winds sensors agree well with the buoy data. The typical root-mean-squared differences of the wind speed and direction are 1 m/s and 20 deg, respectively, while no significant dependences on the wind speed are discernible. The collocated data set is also used to explore differences of wind speed and direction against oceanic and atmospheric parameters and footprint positions. Residuals of the wind speed and direction show slight dependence on the cross-track cell locations, which correspond to combination of the azimuth observation angles. The wind speed residuals exhibit no significant dependences on the oceanic and atmospheric parameters, such as the sea surface temperature, air-sea temperature difference, and sea state