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 degrees S have been used to investigate the characteristics of the bulk (BSST) minus skin (SSST) sea surface temperature difference (Delta T), Delta 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 value of 0.27 K +/- 0.28 K. Delta T in all cases has no dependence on the 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 turbulence reduces Delta T to a mean value of zero, and there is no evidence of any further wind speed dependency. The fact that a negligible Delta T exists in high wind speed conditions suggests that it can be appropriate to use BSST observations to validate satellite SSST measurements and that these are the preferred conditions in which to merge satellite-derived SSST and pseudo-BSST data. The variability of Delta T found in the data indicate that it is unwise to assume a mean global Delta 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.