The Numerical Experiment Research of the Summer Monsoon Onset Mechanism in SCS
Zhu Qiangen and Xu Guoqiang (Nanjing Institute of Meteorology, Naming 210044)
In the context of 3 numerical experiments and the comparison of SCS summer monsoon onset in 1998 and 1996 as well as secular statistical data, results show that the onset time mainly depends on the circulation feature around SCS rather than the SST and its meridional gradient in SCS. In the last 10 days before the SCS summer monsoon onset, the circulation feature over 850 hPa level pres- ented that the subtropical ridge is in west Pacific ocean and extends westward from the Pacific Ocean through the Philippines to SCS. There are a wide low trough from the Arabian Sea to Indo-China. The south Asia high over 200 hPa level was located at the Arabian Sea and SCS and its center was locates at the low latitude of the Bay of Bengal east side and Indo-China west side. The northern region was control of west wind.