Seasonal Transformation Of Upper Layer Circulation In The South China Sea

The circulation movement is strong restricted by structure of the rhombic abyssal plain and distributional features of the submarine relief in the South China Sea where the ocean space is wide and deep. The Y-direction of the rhombic abyssal plain almost accords with the monsoon tend. So it leads to extremely profitably on the development of the drift. Furthermore, it makes all kinds of upper layer circulation systems that alternately controlled by the aestival and the hiemal monsoon in different season. The article summarizes the affect factors, research stage and research methods in the upper layer circulation of the South China Sea and gets current fields of Jan., Apr., Jul. and Oct. which represents the four seasons through the GDEM data and P-Vector method. Base upon the analysis about the structure characteristic in different season, the results shows that the upper layer circulation of the South China Sea has appear obvious seasonal transformation. It is found that the hiemal circulation, which includes few smaller cyclonic current, appears the cyclone pattern as a whole. In contrast, the aestival circulation shows the anticyclone pattern and its vertical structure has few changes in that season. Combine with the data of UCM (Ultrasonic Current Meter), the original verification can be got for the theoretical analytic result. Moreover results of P-Vector is almost accord with the surface layer geostrophic current of the South China Sea that is got by data of TOPEX/POSEIDON satellite remote sensing altimeter. The aestival current field is also found that correspond with the stream function distribution which received by the aestival surveying of South China Sea in 1998 and 2000. Finally, the article discusses the factors that influence calculation and actual measurement current field. It also gives further information about the South China Sea Warm Current and the Kuroshiomakes thf4j|ï¿¡foence*Ojj;Jhje circulation.:...