CHARACTERISTICS OF MEI-YU PRECIPITATION AND SVD ANALYSIS OF PRECIPITATION OVER THE YANGTZE-HUAIHE RIVERS VALLEYS AND THE SEA SURFACE TEMPERATURE IN THE NORTHERN PACIFIC OCEAN

Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and HuaiheRivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and theirrelationships with the sea surface temperature in northern Pacific are investigated using such methods asharmonic analysis, empirical orthogonal function (EOF), composite analysis and singular valuedecomposition (SVD). The results show that the temporal evolution and spatial distribution of Meiyuprecipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annualand inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and themonthly sea surface temperature anomalies (SSTA) lies in the west wind drift of North Pacific, whichinfluences the precipitation anomaly of Meiyu precipitation over a key period of time from January toMarch in the same year. When the SST in the North Pacific west wind drift is warmer (colder) thanaverage during these months, Meiyu precipitation anomalously increases (decreases) in the concurrent year.Results of SVD are consistent with those of composite analysis which pass the significance test ofMonte-Carlo at 0.05.