The water circulation under the influence of a weak gradientfield of atmospheric pressure off Vietnam in spring 1999

Abstract

On the basis of hydrodynamic model we calculated water circulation along the central coast of Vietnam using the data obtained during the April-May 1999 expedition. For this purpose the classification of atmospheric processes over the East Sea was used. From three types of atmospheric processes over the ES we chose the most favorable type – that of "weak gradient field". As a result, obtained were the maps of water circulation at the sea surface, in the 0-200 m layer and in the layer from the surface to the bottom of the investigated area. According to our calculations, clearly noticeable are two anticyclones in the north and in the south of the studied water area and one cyclone in the center of it. These hydrodynamic structures can be traced from the surface to the bottom. Therefore, in the spring of 1999, the current field changes its winter cyclonic circulation to summer cyclonic circulation. As a result, mixed hydrodynamic structures are formed being influenced by both persisting winter and already coming summer monsoons. In general, certain quasi-stationary regularities and regional specific features of water circulation have been found in the spring time.