Precipitation Distribution Pattern Of China In July And Its Cause

This study, based on the monthly precipitation data at 160 stations of china in July from 1951 to 2000,divided Chinese precipitation into seven climatic patterns by using empirical orthogonal function(EOF) and cluster analysis ; the seven patterns are named as follows: south China pattern ,ChangJiang pattern ,Huai River pattern ,north China pattern ,two rain belts(main rain-bands in south China)pattern ,two rain belts(main rain-bands in north China)pattern ,drought pattern The correlation coefficient and probability for every pattern are calculated and checked .The 500hPa height field ,lOOhPa height field and SST anomalies field in July for every pattern ,and subtropical high characteristics ,polar vortex characteristics in previous stage (from January to June) for every pattern have been analyzed and compared respectively , we achieved several interesting results The relationship between precipitation pattern in July and precipitation pattern from June to August (JJA) is analyzed , we found that it抯 60% is in good agreement. The precipitation pattern of July responded to ENSO is also discussed and the result shows that 80% of pattern ChangJiang tend to occur in the following year of Elnino.