The Water Circulation of the South China Sea in a Zone of the Vietnamese Сurrent under the Influence of Southern Tropical Cyclone in Spring of 1999: Results of Numerical Modeling

Vlasova G. A., Nguyen Ba Xuan, Demenok M. N.

The integrated water circulation of the South China Sea in the area of coastal Vietnamese Current during transitional spring period (May 1999) has been calculated on the basis of numerical modeling. The South China Sea considerably influences the climate regime in South-East Asia, including the Far East of Russia. Here the tropical cyclones of the destructive power coming from the western Pacific or incipient in the South China Sea are developed. This specified year was selected in connection with this period of large-scale international expedition Fisheries Association of South-East Asia and Japan, the data of which are presented by Vietnamese colleagues. Spring season is used as an example of the transition from winter to summer because it’s poorly investigated. Synoptic processes in the region significantly influence the seasonal the nature of Vietnamese Сurrent. This current is directed from north to south in winter under the influence of the northeast monsoon, thus forming the cyclonic water circulation. This current is directed in the opposite direction in the summer under the influence of the southwest monsoon, forming an anticyclonic circulation. The calculations were performed for the synoptic situation, which is characterized by the presence of tropical cyclone in the southern part of the South China Sea. Results of modeling have showed that two anticyclonic and separating its cyclonic gyres exist in the specified period in the studied area. As a result, two zones of different water modifications within the Vietnamese Current are formed: water masses are transported from south to north in the northern and southern parts of the region (summer regime), and in the central part — from north to south (winter regime). On this basis, it was concluded about a transitional character of the chosen time interval when influence has not yet left winter and already coming summer monsoons affects.

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