Evaluation of the diurnal warming of sea surface temperature using satellite-derived marine meteorological data

In order to produce a high-quality sea surface temperature (SST) data set, the daily amplitude of SST (DeltaSST) should be accurately known. The purpose of this study was to evaluate the diurnal variation of sea surface temperature in a simple manner. The authors first simulated DeltaSST with a one-dimensional numerical model using buoy-observed meteorological data and satellite-derived solar radiation data. When insolation is strong, the model-simulated 1-m-depth DeltaSST becomes much smaller than the in situ value as wind speed decreases. By forcibly mixing the sea surface layer, the model DeltaSST becomes closer to the in situ value. It can be considered that part of this difference is due to the turbulence induced by the buoy hull. Then, on the assumption that the model results were reliable, the authors derived a regression equation to evaluate DeltaSST at the skin and 1-m depth from daily mean wind speed (U) and daily peak solar radiation (PS). DeltaSST is approximately proportional to In(U) and (PS)2, and the skin DeltaSST estimated by the equation is not inconsistent with in situ observation results reported in past studies. The authors prepared maps of PS and U using only satellite data, and demonstrated the DeltaSST evaluation over a wide area. The result showed that some wide patchy areas where the skin DeltaSST exceeds 3.0 K can appear in the tropics and the mid-latitudes in summer.