Characteristics Of Precipitation In Flood Period Of The Eastern Part Of Northwest China And The Response Of Surface Sensible Heat Flux Over The Mid-High Latitudes Of The Eurasian

This paper using the precipitation data of 156 station in east part of northwest China, analyzes the change of precipitation characteristics of the two zone in the east part of northwest China in late spring and early summer (may to June), summer (July to August), early autumn (September). Using similarity method, the distribution of precipitation in east part of northwest China can be divided into 4 types:the consistent wet(dry) type and southern wet(dry) northern dry(wet) type. Comparing three precipitation period’s distribution types, and analyzing the influence of Global warming in precipitation distribution types. At the same time, analyzing possible linkage between surface sensible heat flux anomalies over the Mid-High Latitudes of the Eurasian Continent and summer precipitation in the Eastern Part of Northwest China.The results showed that:1. Tendency of precipitation in each period of the east part of northwest China was different. Precipitation of late spring and early summer increased significantly within 52 years. But precipitation of summer decreased significantly within 52 years. Precipitation’s trend of early autumn was more-less-more. Although the tendency of precipitation in each period of the east part of northwest China was different, but the precipitation has a decreasing trendency after global warming in each period. And the precipitation of northeast of plateau has decreased significantly. After the beginning of the 21st century, precipitation has increased in the all region. That may caused by the weakeness of cold source in winter and the enhancement of heat flux in summer over the Mid-High Latitudes of the Eurasian Continent.2. The sensitive area of precipitation anomaly of the the consistent type was moved to the south gradually in east part of northwest China. The sensitive area of southern wet(dry) northern dry(wet) type was moved to the north gradually. And the consistent dry type’s frequency was the biggest. But after the global warming, although the consistent dry type was the major type, consistent wet type’s proportion was larger. And the consistent dry type’s proportion was smaller.3. Heat flux anomaly over the Mid-High Latitudes of the Eurasian Continent affects the precipitation in the summer in Eastern Part of Northwest China. Surface of the Mid-High Latitudes in Eurasian Continent is a cold source of sensible heat, which is strong cold air action to the atmosphere. During strong year of the cold source of sensible heat, the atmospheric transmission to the surface was much stronger. That may lead to the transmission from surface to atmosphere much stronger in summer. And that also lead to the Ural blocking high and Mongolian low were strength. The northwest Pacific subtropical high was stronger and more westward than normal. There are much warm moist air flows in low-level. Position of westerly jet was more northward than nomal. Southern pressure high was in the east. Middle and upper of troposphere has updraft.There also has the divergence of the water vapor in Eastern Part of Northwest China. The above reasons resulted in increased summer precipitation over the Eastern Part of Northwest China. During weak year of the cold source of sensible heat, the above reasons resulted in decreased summer precipitation over the Eastern Part of Northwest China.