Yamase-derived Gap Winds Off the Western Hokkaido Coasts and Their Effects on Sea Surface Temperature Fields

Suttu, which is located in the western Hokkaido, is known to be the 4^th strongest windy place in Japan, where topographical gaps efficiently develop strong winds. These gap winds over the ocean and their effects on sea surface temperature (SST) fields are investigated by scatterometer- and synthetic aperture radar (SAR)-observed wind fields and the Advanced Very High Resolution Radiometer (AVHRR)-derived SST data. The SAR wind field observed by a wide-swath ScanSAR mode reveals a series of wind jet/wake patterns, which correspond to upstream land topography. The strong jets extend offshore over 100 km. It is found by several SAR-derived wind fields that these gap winds develop under the condition of upstream easterly winds. The easterly winds are common in spring and summer, which are known as the Yamase phenomena in northern Japan. Low/high SST patterns, which correspond to the jet/wake, are frequently observed off the western Hokkaido coasts in summertime. We create a composite image of the SST spatial anomalies for windy days, based on in situ wind measurements in Suttu. The composite image shows well-defined local SST cooling/warming stripes along general wind jet/wake regions. These are probably induced by the difference of the diurnal warming amplitude.