Research On Extreme Heavy Precipitation Event Characteristic And Analysis Of Causes

Based on 314 stations daily precipitation datasets in China and NCEP/NCARreanalysis height fields, wind fields, sea surface pressure fields, specific humidity,surface pressure and NOAA reconstruct sea surface temperature from 1955 to 2004,temporal and spatial characteristic and inter-annual inhomogeneity of annual extremeheavy precipitation events are analyzed. Moreover possible effect mechanism ofsummer extreme heavy precipitation events is also discussed, the result are asfollows:(1) It is found that average spatial distribution of annual extreme heavyprecipitation events exist prominence difference in China, it is the primary mode thatnorth of Changjiang-Huaihe, Hunan, southwest of Sichuan, Xizang and west ofXinjiang show reverse change characteristic with others regions. Trend change andsudden change characteristic of annual extreme heavy precipitation events are alsoexist clear difference in every sub-regions.(2) Average spatial distribution of annual extreme heavy precipitation eventsconcentration degree and concentration period show "low-high-low" characteristic,change characteristic of the concentration degree and concentration period also existclear difference in every sub-regions. It is proved that annual precipitation is morelack if annual extreme heavy precipitation event is more concentrated, vice versa, butrelativity is low between the concentration period and annual precipitation.(3) In former winter equator middle-east Pacific ocean is key area to effectsummer extreme heavy precipitation event of North China, in anomaly warm winteryears of equator middle-east Pacific ocean, the area shows anomaly updraft atcorresponding phase and anaphase spring, this cause anomaly strong Hadley cell inmiddle-east pacific, and compel 500hpa height field to show PNA teleconnection, itdisplays WP teleconnection at anaphase summer, thus intensity of west Pacific oceansubtropical high boost up, its area augment and west boundary prone to west from winter to summer, North China is located confluence place between partial southwind and partial north wind at anaphase summer, and easily occur extreme heavyprecipitation event. Vice versa.(4) In former Winter tropical west Pacific ocean is key area to effect summerextreme heavy precipitation event of Northeast China and south of Changjiang, inanomaly warm winter years of tropical west Pacific ocean, from winter to summerthe middle-low latitude area shows anomaly updraft and middle-high latitude areashows anomaly downdraft, low layer prevail anomaly partial north wind and highlayer prevail partial south wind, the anticyclone upright circumfluence circle buildupintensity of east Asia winter monsoon and weaken intensity of east Asia summermonsoon, cause vapor transportation only reach south of Changjiang, and partialwest draft prevail in Northeast China in summer, because of shortage vapor source,summer extreme heavy precipitation event partial lack in Northeast China, but it isplenitude in south of Changjiang. Vice versa.