Winter, The Yellow Sea Sea Circulation And Expansion Of The Yangtze River Diluted Water

In this paper making use of a three dimension high resolution numerical model which takes into account various dynamical factors, Shelf currents in Yellow Sea and East China Sea are simulated exactly at first. Then based on the results the impact of wind and runoff on the expansion of the Changjiang diluted water are simulated and analyzed.This paper simulates the M2 tide before the other numerical experiments. The results testify that the numerical with the tidal current open boundary condition are consistent with those with the tidal level open boundary condition, and provide the boundary data for the experiments. In the winter wind-driven current field, the current flow south from the south coast of the Bohai Sea gulf to the west coast of Taiwan Strait. The surface currents strength are bigger than the bottom currents. And an ocean current in the south of the Yellow Sea flows north, constituting a cyclone type circulation with the wind-drift coast current. In the numerical experiment whose residual currents are induced by the boundary forces, there are strong currents invading the shelf in the area to the northeast of Taiwan. Another ocean current flows northeast along the steep continental shelf. The current divides into two branches at 127.6°E, 30°N. One branch flows north through the Tsushima Strait; the other still flows northeast, then turns to southeast to the southwest of Kyushu due to the impact of topography. In the density current field, a strong ocean current flows northeast along the shelf at surface. But the bottom current field is in disorder. In Changjiang estuary area, the surface density currents flow southeast mostly, and a cyclone type circulation appears in Hangzhou gulf. But the bottom currents flow north in the area near Changjiang estuary and Hangzhou gulf, just opposite to the surface currents. The numerical experiment reconstructed fairly successfully the circulation patterns of the Kuroshio, the Taiwan Warm Current, the Tsushima Warm Current and coast currents.In winter under the effect of north wind the Changjiang Diluted Water flows south in a narrow area along the coast. The intensity of the Changjiang Diluted Water on the high salt sea water is affected in evidence by the wind. In the case of increaseof wind speed, the diluted water away from Changjiang estuary turn south quickly, the current speed is enhanced obviously. And the Taiwan Warm Current dies down clearly in a trend for flowing north. In the case of decrease of wind speed, the surface diluted water trends east more, the variety of the current speed is not very obvious. And the Taiwan Warm Current flowing north in this area is enhanced. In the case of increase of runoff, the surface diluted water enhances greatly, and a very strong salinity front appears near the Changjiang estuary. In the case of decrease of runoff, the speed of the diluted water at the surface and bottom weakens. The current field far away from the Changjiang estuary area doesn't change much.