OBSERVATIONS OF THE OCEANIC THERMAL SKIN IN THE ATLANTIC-OCEAN

An extensive set of measurements made along a transect of the Atlantic Ocean covering a latitude range of between 52 degrees N and 20 degree s S have been used to investigate the characteristics of the bulk (BSS T) minus skin (SSST) sea surface temperature difference (Delta T), Del ta T is highly variable and has an overall mean value of 0.35 K +/- 0. 35 K, a daytime mean value of 0.49 K +/- 0.39 K and a nighttime mean v alue of 0.27 K +/- 0.28 K. Delta T in all cases has no dependence on t he amount of cloud cover. At low wind speeds, Delta T increases as the wind speed increases. At a wind speed > 10 m s(-1), wind induced turb ulence reduces Delta T to a mean value of zero, and there is no eviden ce of any further wind speed dependency. The fact that a negligible De lta T exists in high wind speed conditions suggests that it can be app ropriate to use BSST observations to validate satellite SSST measureme nts and that these are the preferred conditions in which to merge sate llite-derived SSST and pseudo-BSST data. The variability of Delta T fo und in the data indicate that it is unwise to assume a mean global Del ta T of 0.3 K. A comparison between several parameterizations of Delta T shows that such parameterizations are unable to describe the Delta T values found in this data set.