Study of the dynamics of wind-driven transports into the Yellow Sea duringwinter

Synoptic wind stresses and surface heat flux force a three-dimensional nume rical ocean model of the Yellow Sea/East China Sea dynamics. The basin resp onse to winter winds is examined through the model output fields. Northerly wind bursts are a frequent winter occurrence in this region. The wind burs ts develop a southward flowing current along the Chinese coast as the wind stress forces fluid out of the Bohai Sea. A north-south pressure gradient d evelops as surface water travels from the Bohai Sea southward, decreasing t he elevation in the north relative to the elevation in the south. Also, a w estward pressure gradient across the Yellow Sea basin develops in response to the wind forcing. The southward pressure gradient forces a bottom flow i n the direction opposite to the wind stress. This return flow is concentrat ed in a deep trough located on the eastern side of the basin. After the nor therly wind ceases the northward transport increases pressure in the north with the result of slowing or stopping the flow northward. At times, pressu re increases in the north sufficiently to force a southward flow in the tro ugh. Following strong northerly wind events, northward transport into the Y ellow Sea occupies the entire trough and may extend into the northern Yello w Sea/Bohai Sea. During periods of calm winds, northward flow usually does not penetrate beyond 34 degreesN in the Yellow Sea. This flow is northward on the western side of the island of Cheju. The flow turns eastward north o f Cheju and then southward, passing through the Cheju-Korea Strait. The win d stress along the Korean coast often deviates from the northerly wind stre ss over the rest of the Yellow Sea. Thus the flow along the Korean coast is not as closely related to the northerly wind bursts as the flow along the Chinese coast. The winter circulation in the Yellow Sea is predominately a barotropic response to winds with fluctuations due to Ekman flow.