WINTERTIME FRONTAL CIRCULATION IN THE YELLOW SEA

Abstract

: At the entrance of the Yellow Sea (YS), warm and saline water is distributed in a tongue shape in winter, while cold water is known to flow out of the Korean and Chinese coastal area. At the same time, a thermohaline front forms persistently at the boundary of the two waters across the YS entrance. We have described detailed frontal structure and circulation using CTD data collected twice in February 2001 and 2003 and by analyzing position data of drifting floats. In February 2001, we observed northwest movement of a float across the northwestern part of the front from the warm water area and this may indicate the onshore intrusion of the warm water toward the Chinese coast. In the Chinese coastal area west of the front, floats moved southeast along the 50 m isobath, approving the existence of a Chinese coastal jet in winter. In February-March 2003, we detected for the first time westward displacements of floats at fast speeds along the northern front. This observation is a new, unexpected finding for the westward along-front flow across the YS entrance. Thus, the westward along-front flow and the southeastward Chinese coastal jet along the tongue-shaped front eventually form a cyclonic frontal circulation, in good contrast with the clockwise turning of the Cheju Warm Current.