Demarcation and Features of Northeast China Rainy Season

Based on the 1951—2001 dekad mean rainfall of 9 stations in northeast China,northeast China rainy season is demarcated.The initiation,termination,duration and rainfall of rainy season are determined and the relationships among these characteristic quantities discussed.The atmospheric circulation variations at the beginning and end of rainy season are compared.And the lag correlation between rainy season characteristic quantity and SST anomaly in tropical ocean key regions is investigated.Results show that:(1) the rainy season begins in the first-second dekad of July,and ends in the first-second dekad of August,and the rainy season rainfall is closely related to the Z index of the total rainfall of 9 stations in summer,indicating that the rainy season rainfall reasonably reflects the summer precipitation features of the region;(2) generally speaking,when the rainy season begins earlier,it always persists for a longer period,and its rainfall is greater,and when the rainy season begins later,the inverse is also true;(3)the northeast China rainy season is principally controlled by the East Asian summer monsoon:when the East Asian summer monsoon strengthens and marches northward,the rainy season begins,and when the East Asian summer monsoon weakens and withdraws southward,the rainy season terminates;and(4)the seasonal SSTA over the tropical ocean is a precursor on the scale of short-range climate prediction to the rainy season features in northeast China.