The thermal skin temperature of the ocean at high wind speed

Extensive in situ observations obtained in the Atlantic Ocean are used to demonstrate the relationship between the wind speed and the temperature deviation /spl Delta/T (defined as the sea surface skin temperature (SSST) minus the subsurface bulk sea surface temperature (BSST)). At wind speeds >8 m s/sup -1/, the variability of /spl Delta/T is diminished and the mean value of /spl Delta/T approximates a constant cool bias of -0.1 K /spl plusmn/0.1 K. At wind speeds below 5 m s/sup -1/ the complicating effect of thermal stratification during the daytime means that the BSST and the SSST should be considered independently of each other. Comparing the field measurements to the output generated by a numerical model of /spl Delta/T we note that the model is able to adequately re-produce the measurements given a heat flux and wind speed measurement over a range of wind speed up to a 16 m s/sup -1/. In high wind speed conditions, we conclude that the BSST is well coupled to the SSST and, if corrected for a small bias, BSST can be used with confidence to validate satellite derived sea surface skin temperatures. This technique will be most useful in remote regions such as the Southern Ocean where in situ SSST are exceptionally difficult to obtain. However, we highlight the need to use in situ SSST observations for satellite validation at lower wind speeds due to the complicating effect of thermal stratification of the ocean surface water. This effectively de-couples the SSST from the subsurface BSST.