Atmospheric Motion Vector Information Revealed By The Upper Tropospheric Circulation Relationship Between The Situation And China's Summer Rainfall Belt

In this paper, allocation analysis between the atmospheric motion vector and precipitation data is made, which verifies that circulations in upper troposphere of summertime rainfall events in China during 1998 - 2002 can be reduced to three typical patterns:1) First one is often seen at the Changjiang river region and in the southeastern China from June to July whose rain belt is associated with an anticyclone ridge at the upper troposphere, with precipitation cells in the diverging area between the subtropical westerly jet and the ridge or in the velocity diverging area of the tropical easterlies north of the ridge ;2) Second one is often occurred in the southeast of china (Hainan, Guangdong, and Guangxi etc.) from July to September with the rainfall center locating on the right side of the upper deformation field and the west of the outflow area of the asymmetry anticyclone;3) The third pattern is frequently happened north of 30°N in china from July to August with the rainfall center lies in the southwesterly in front of the westerly trough which occurred primarily in the upper of the northern China.In comparison, air divergence in the upper troposphere is commonly seen in these three circulations. Having a small wind component inwards, the area at the upper troposphere corresponding to the precipitation areas in the first and second patterns has anticyclone vorticity, while the precipitation areas in the third pattern is under the positive vorticity advection zone in front of upper westerly trough , which has a large component inwards. Besides, compared to the first one, happening around higher latitudes, with prominent jets and northerly component on the ridge, the second one occurs around lower latitudes, with indistinctive jets and southerlies on the ridge.The dynamic significances of the circulation pattern of Jun 26th ,1999 are documented at the end of this paper from the mass angular momentum and moisture circulation perspectives, which suggest that the configure having cyclonic inwards and anticyclonic outwards in lower and upper troposphere respectively is of great benefit to the conservation of mass and angular momentum in the whole atmosphere.