Analysis On The Characteristic And The Key Factors Of The Precipitation And Anomaly In Northwest China And Tibetan Plateau Northeastern Side

Based on the precipitation analyses in Northwest China and the relation between the Northern Cyclone and the precipitation, investigation of precipitation anomalies in Tibetan Plateau northeastern side(TPNES) and corresponding general circulation has been performed. In the study of the mechanism of the precipitation anomalies, the discovery is then chiefly to study the effect of SSTA on rainfall in floods season in TPNES, concluding that there is a high correlation between the floods season precipitation in TPNES and Australia eastern SSTA and SSTA distribution. Some conclusions in this paper as followed:(l)Arid is the most fact of the precipitation in Northwest China. The main anomaiy structure is wet(or dry) in all area pattern, and the secondary anomaly structure is wet(or dry) in east and dry(or wet) in west pattern, and the last is wet(or dry) in north and dry(or wet) in south pattern. Moreover, the correlation between the floods season precipitation and the Northern Cyclone is fine.(2)TPNES precipitation anomalies is the highest in Northwest China, and the dry years are more than the wet years, whereas no the lasting dry years. In the recent forty years, the precipitation in June is rising slowly, and no remarkable changes in July, and descending in August. Furthermore, the floods rainfall and air temperature are all increasing slowly in 40 years.(3) the polar eddy, the west circumfluence on 500hPa medium latitudinal region ands subtropic circumfluence are the key systems of TPNES floods precipitation and, the wet years have abundant vapor, moreover, the omga is positive in all atmosphere.(4)There is apparent negative correlation between floods season precipitation in TPNES and SSTA(l-3 monthly averaged in former year)in eastern Australia, especially the higher correlation in the "KEY region" (165°~175°E, 31°~21°E) .(5) The "seesaw" type of SSTA distribution is the dominate SSTA distribution in equator and south Pacific Ocean correlating with the floods season precipitation anomalies in TPNES.