Wintertime Large Temperature Inversions in the Yellow Sea Associated With the Cheju and Yellow Sea Warm Currents

摘要

Large temperature inversions in the Yellow Sea during winter were investigated by analyzing conductivity-temperature-depth data collected in January and February 1986, April 1996, and February 1997. Large inversions with temperature differences across inversion layers greater than 2 degrees C were observed at three places: southwest of Korea, southeast of the Shantung Peninsula, and on the northeastern flank of the Changjiang Banks. Pronounced thermohaline fronts were commonly established where warm offshore waters with high salinity were found below cold coastal waters with low salinity. In the southwestern area of Korea, where the front develops in an east-to-west direction, the Cheju Warm Current water flows eastward to the south of the front, while north of the front, cold Korean coastal water flows westward. In the southeastern area of Shantung Peninsula, where the front forms in northeast to southwest, the Yellow Sea Warm Current flows northeastward on the offshore side, while cold Chinese coastal water flows southwestward. Moderate temperature inversions were observed midwest of Korea and on Changjiang Banks when warm offshore waters extended into cold coastal areas. In the inversion areas, warm waters are heavier than cold waters, reflecting a stronger contribution of salinity to density than that of temperature. Consequently, isotherms and isohalines in the inversion areas commonly decline downward toward cold water areas. We concluded that the occurrence of large inversions is closely related to the advection of the Cheju Warm Current and Yellow Sea Warm Current waters to the thermohaline frontal zones where the warm offshore waters underlay lighter cold coastal waters.