Diagnostic Analysis on Heavy Torrential Rain with Typhoon Depression in Eastern Jianghuai Region in 2008

NCEP reanalysis data and doppler radar sounding data were taken for diagnostic analysis of the heavy torrential rain process in eastern Jianghuai caused by low pressure of Fenghuang typhoon depression.The results showed that low trough of middle and low layer and high layer vortex were the main influencing system of the process and deep low-pressure system was its important characteristics.The abundant and deep moisture convergence,lower-level convergence,lower level positive vorticity and upper-level minus vorticity and intensely vertical ascent motion composed the favorable environment field condition.The torrential rain region located in the strong gradient region western to positive vorticity and below of the center of vertical ascent motion.During the torrential rain,3 middle-level echo strips combined into the main echo and caused the strong convection in combined region.