Characteristics of the satellite-derived sea surface temperature in the oceans around Japan

We compare the sea surface temperatures (SSTs) derived from NOAA/AVHRR data through the multi-channel sea surface temperature (MCSST) algorithm with the in situ SSTs reported from ships and buoys during November 1988-May 1991 in the oceans around Japan. The weekly averages of both the SSTs are computed in 1°-grids. We find from this comparison that the satellite-derived SSTs are lower than the in situ SSTs by more than 0.5°C on the average in the Yellow Sea, the north of the Japan Sea and around the Kuril Islands. On the other hand, the satellite SSTs are higher than the in situ ones by more than 0.5°C in the regions of the Tsushima and Tsugaru warm currents. Furthermore, we find that the most dominant variation of the differences is an annual cycle in the regions north of 40° latitudinal line. In these regions, the satellite-derived SSTs are higher (lower) than the in situ SSTs by more than 1.0°C in summer (winter) on the average. Because there is not such a large amount of water vapor or volcanic aerosols that cause a large error through the MCSST algorithm over the regions, the systematic biases may be related to vertical temperature structures in the ocean surface layer, formed by the strong monsoon. In order to obtain more accurate SSTs from satellite observations in these regions, the characteristics of the vertical temperature structures in the ocean surface layer are needed to be investigated in detail.