Diagnostic Analysis on the First Summer Rainstorm Process of Central Yunnan in 2012

Based on intensive observations, hourly FY-2E infrared TBB data, Doppler radar echo data and analysis data of NCEP (1°×1°, 4 times a day), the first rainstorm process in central Yunnan from 1 June to 2 June in 2012 are diagnostically analyzed using meso scale filtering method and generalized moist potential vortices theories (GMPV).The result shows that this strong precipitation process is caused by cold front and sheer, which is typical in central Yunnan. Shear line, mesoscale convergence line and meso-β-scale low vortex are significant at 700 hPa after mesoscale filtering, but they are not obvious in largescale original stream fields. So the direct causes for this rainstorm process are mesoscale weather systems. It seems apparent that the rainstorm always happens at the side which TBB gradient is higher in the convective cloud clusters by hourly FY-2E infrared TBB data. After analysis on Doppler radar echo data, there is a large area of flocculent echoes at the strong precipitation region, and then some convective clouds develop in these flocculent echoes. Distribution of rainfall is not uniform in space and the efficiency of rainfall is high because of uneven distribution of echoes in space, low height and dense structure of echoes. The source region of water vapor is the Bay of Bengal. The water vapor convergence zones have a good correlation with the position of surface cold front, shear line, mesoscale convergence line and meso-β-scale low vortex at 700 hPa. The ground precipitation strengthens when the center of vapor convergence area at 700 hPa and 850 hPa are superimposed.The positive anomaly of GMPV at mid-low layers over strong rainfall area can reflect characteristics of high water vapor convergence. Vertical distribution and change of GPMV at the low layer of single station show good indicative significance in this strong rainfall process. The rainfall is intensified when the positive anomaly of GPMV at the low layer of single station increase, and vice versa. The GMPV at 800 hPa has an indicative effect on the location of heavy rainfall. The area of GPMV positive anomaly is always located in the center of strong precipitation and its surrounding area, but the center of strong precipitation is not coincided with the center of positive anomaly of GMPV completely. The forecast of this process will be better if the circulation patterns are analyzed synthetically, and the generalized moist potential vorticity theories are used as well.