Characteristic of South Asia High Activity and Its Relation with the Precipitation of East China in Summer
The daily mean variations of the ridge line and the east ridge point of South Asia High (SAH) and the relation with precipitation of East China in summer are studied using the about 30-year (1979-2007) Daily NCEP/DOE Reanalysis 2 data and observational data at 595 stations given by National Meteorological Information Center. It is founded that the ridge line changes abruptly northward in the third pentad of May. The time of abrupt change is one pentad before the one of SCS Summer Monsoon onset. There is a southward retreat of the ridge line in the last decade of April during the northward movement. The middle ridge lines keep more northern positions and jump northward earlier than the east ridge lines in late April while they locate southerly after August. The SAH has a eastward advancing from the mid of June to early July. There is a weekly time scale oscillation of the east ridge point. The simultaneous correlation shows the longitudinal positions of the east ridge point are better characteristic parameters of SAH when analyzing the summer precipitation of the Yangtze River-Huaihe River Basin (YHB) and South China. But when turning to the summer rainfalls in the lower reaches of the Yellow River basin, the ridge line of SAH is a relatively advisable choice. Composed analysis indicate that YHB, some parts of Northeast China are in a flood period and South China are in a drought period, meanwhile SAH intensity increases during east deviation years, and vice verse during west deviation years.
East ChinaEast ridge point of the SAHSummer precipitation
NETL
NSTL
万方数据
维普
