Analysis Of Meteorological Factors Of Regional Heavy Rainfall In East China During Meiyu Period

Using the data of 113 cases during the Meiyu period from 1990 to 1999, the correlation analysis and composite analysis were conducted to examine the possible connections between regional average daily rainfall in different areas of East China and the analysis fields of various dynamic and thermal variables at four different leading time from 24 hour to rain occurring time. The evolutions of significant features which favor the heavy rainfall in northern Zhejiang were emphatically investigated, then the prophase signatures of regional heavy rainfall in other sub-areas of East China were compared with those in northern Zhejiang, mainly to show their differences Finally, the physical conceptual models of heavy rainfall in East China were developed . The research results will help us to improve the short range forecast of heavy rainfall during the Meiyu period in different areas of East China.Result shows: dynamic and thermal variables put up different characteristics because geography of place differs in different areas of East China, but they have similar characteristics when in strong raining of Meiyu. Eastward moving of low pressure and maintaining in the middle and lower reaches of the Yangtze River accelerate strong convections to take place and develop. While the disturbances of vortex convergence reinforce because of the superposition of Meiyu front and deep shear, and the coupling of upper-level and low-level jet streams, then touch off the instability of humid symmetry, so that convection system happen and develop. Coupling of high-level and low-level convergence and divergence strengthens the vertical motions in troposphere, and the upper of precipitation area easily come to being the large-scale circumstance conditions of high temperature and high humid. These meteorological characters have important effects to heavy rainfall in areas of East China, so finding out these meteorological characters of different areas have important meanings in order to forecast heavy rainfall of Meiyu in East China.