Satellite observations of sea surface temperature and sea surface wind coupling in the Japan Sea

We investigate ocean-atmosphere coupling in the Japan Sea by using microwave satellite measurements of sea surface temperature (SST) and sea surface wind from 1 June 2002 to 31 December 2004. First, it is observed that instantaneous wind speeds are modified by SST front meanders in widespread areas in the Japan Sea. Increased/reduced wind speeds are found over warmer/colder water. Then, we compute SST and wind speed anomalies by spatial high-pass filtering in order to present their time evolution along 132°E. SST and wind speed anomalies are negatively correlated off Vladivostok (>41 °N) in winter. This is consistent with the interpretation that there is large turbulent heat flux loss due to the wind speed maximum off Vladivostok or the gap exit region of the northwesterly wind jet. However, except for this region in winter, we find strong positive correlation between SST and wind speed anomalies throughout the year at any latitudes. Wind speed anomalies are linearly related to SST anomalies. Meanwhile, we identify two pairs of positive and negative SST anomaly bands in the time-space structure of the Japan Sea and compare the band locations with meridional SST gradient magnitude. As a result, the two boundaries of the SST anomaly bands are associated with the Polar Front and the Tsushima Warm Current front. Additionally, it is found that discontinuous SST anomaly patches correspond to oceanic eddies. These results lead to the conclusion that sea surface winds over the Japan Sea come under the influence of those SST frontal systems.