The Correlation Characteristics Between The Main Precipitation Patterns In Eastern China And The Thermodynamic Factors Over The Tibetan

In this paper, the correlation between the main summer precipitation patterns of eastern China and the spring or summer apparent heat source(Q1) over Tibetan is investigated with the methods like EOF, morlet wavelet analysis, correlation analysis, composite analysis,by using observation precipitation data from2474weather stations and NCEP/NCAR reanalysis datasets. The effect of the spring or summer apparent heat source(Q1) over Tibetan to the summer precipitation patterns of eastern China is also discussed from the point of three-dimensional structure.conclusions are as follows,Firstly, The summer precipitation of eastern China can be divided into three patterns, Southern China-Jianghuai, Middle and lower Yangtze River and northern China pattern. Judged from change features, the rain-belt of east China has the trends of withdraw south and then move northword in nearly50years. The Q1of spring or summer over the Tibetan has a good continuity for both time and space. Because of the terrain of the Tibetan, from spring to summer, the Tibetan becomes a lifted big heating source, whose heating effect cannot be ignored.Secondly, one calculates the correlation between the Principal component of precipitation and Q1for each level of the Tibetan, seeking for the Ql-key-area well correlated with the precipitation patterns, which will provide information for the precipitation forecast. Based on the Q1-key-areas above,one can come to the conclusion of three-dimensional structure of spring or summer Q1that well correlated with the precipitation patterns and the continuity from spring to summer of these three-dimensional structures. The conclusions are as follows,(1)In spring, low to medium layer Q1over middle Tibetan is weak, and to summer, the whole layer Q1over middle Tibetan is weak, the Southern China is wet and Jianghuai dry;(2)In spring, medium to high layer Q1over middle-northern Tibetan is weak, and to summer, the low to medium layer Q1over northern Tibetan is weak, the low to medium layer Q1over southeastern Tibetan is strong, Middle and lower Yangtze River is wet;(3)In spring, medium to high layer Q1over middle-southern Tibetan and low layer Q1over northern Tibetan are strong, and to summer, medium to high layer Q1over middle-southern Tibetan and low layer Q1over northern Tibetan are still strong, northern China is wet.Finally, analyze the contribution of three-dimensional Q1to the summer water vapor transportation fields. The results show that (1)Three-dimensional Q1of spring affects the summer water vapor transportation fields through the northwards water vapor transportation at southeastern Tibetan, when spring Q1is strong, northwards water vapor transportation at southeastern Tibetan is strong, doing a favour for the north-eastward transportation of the water vapor transportation which come form Bengal and south China sea to eastern China from southern and southeastern Tibetan, leading to ’North wet-South dry’.(2) Three-dimensional Q1of summer influences the summer water vapor transportation fields by affecting the local circulation over and around the Tibetan. The strong local Q1can lead to abnormity of local circulation, and then influence the water vapor transportation around the Tibetan and abnormity precipitation distribution at the lower regions.