Implications of the oceanic thermal skin temperature deviation at high wind speed

Abstract

Extensive oceanographic and atmospheric observations obtained during three independent experiments in the Atlantic Ocean are used to demonstrate the relationship between wind speed and the temperature deviation ΔT, which is defined as the sea surface skin temperature (SSST) minus the subsurface bulk sea surface temperature (BSST). At wind speeds < 6 m s-1, the variability of ΔT increases because thermal stratification complicates the measurement and interpretation of ΔT: extreme ΔT magnitudes of > 1.5 K are common during periods of high insolation. The variability of ΔT at night is reduced and extreme cool skin temperatures of < -0.5 K are recorded. In all cases, at wind speeds > 6 m s-1, the variability of ΔT is diminished and the mean value of ΔT approximates a cool bias of -0.14 K ±0.1 K. We conclude that BSST measurements obtained at wind speeds > 6 m s-1, when corrected for a small (- 0.14 K) cool bias, are representative of the SSST and can be used with confidence to validate satellite derived SSST. When the wind speed is < 6 m s-1 and the magnitude of ΔT is high, in situ radiometric SSST measurements are mandatory to validate satellite derived SSST.