Reduced horizontal sea surface temperature gradients under conditions of clear sky and weak winds

The reduced horizontal sea surface temperature (SST) gradients under the conditions of clear sky and weak winds are discussed. In the case of weak surface wind speed, less than approximately 5 m/s and a clear sky with strong insolation, two effects can occur that may lead to misinterpretations. A shallow layer of warmed water near the sea surface can develop, which makes the SST not representative of the bulk of the mixed layer of the ocean. If horizontal temperature gradients exist in the surface water, the simultaneous cooling from the sea surface by evaporation and longwave radiation would be larger from the warmer water than from the cooler side of the gradient leading to greater net heating on the cool side.