Sea surface temperature changes with katabatic winds observed from IR and SAR images

摘要

Katabatic winds generally flow from mountains or hills down to their lee side in the paths of depression. If the mountainor hill is near a coast, the katabatic winds may cause imprints on the sea surface. The katabatic wind pattern shown on asynthetic aperture radar (SAR) image is a bright-dark region that mirrors the coastal mountain topography. In this study,bright regions on SAR images caused by katabatic winds are found in the west of Hengchun Peninsula where is locatedin the southern Taiwan. The katabatic winds cause the sea state variations and then the sea surface temperature changes.Relationships between normalized radar cross section (NRCS) and sea surface temperature (SST) as well as thetemperature difference between air and sea in the west of Hengchun Peninsula are investigated to find out the air-seaheat transfer. The results show that 1) the SST decreases when the NRCS increases, that is, the higher wind speed wouldcause the SST lower; and 2) the gradient of linear relationship between NRCS and SST is related to the temperaturedifference between air and sea, that is, the higher temperature difference could increase the release of heat from theocean to the atmosphere.