Feature Analysis On Weather Characteristics And Convective Parameters Of Strong Convective Weather In Yangtze River Delta

With global warming, torrential rain, hail, tornado, thunderstorms and gusts became disastrous. It’s always a key and main point since its short lifetime and sharply development. Recently more and more researches have been done about disastrous convective weather. Due to the low resolution of space and time of the data and its high relevant to the terrain, it remains unforecastable. For example, in addition to the large-scale circulation, distribution of tornado and hail are highly dependant to sea level elevation, and yet, the numerical model has not reached this accuracy. The research area is Yangtze River Delta which includes Jiangsu Province, Zhejiang Province and Shanghai. Torrential rain, tornado, hail, thunderstorm and gust have been studied. Comprehend the development of the severe weather by building the weather conceptual models and physical parameter calculation. High-sensitive parameters have been applied to the potential forecast of severe weather.This paper mainly contains five parts, including analyzing strong convective weather by checking up the data of hail, tornado, thunderstorms and gusts from1971-2006, and per hour precipitation from1991-2009.Results show that (1) hail days has small changes from1971to1995, and then it has a sharp decrease. Tornado, thunderstorm and gust have a slight decrease and increase slowly from about2002.(2)Most severe weather occurred in September.(3)Spatial distribution shows that hail often take place in north-east of Jiangsu and in middle of Zhejiang Province. Hail occurred most in Hangzhou Bay. Thunderstorm frequently takes place in the south, while the gust comes up most in the east. Coefficient of variation calculation shows that days of thunderstorm occurrence varied most in the east of Zhejiang, and in the middle and north of Jiangsu it displays big value.The following part of the paper mainly concerns on the composited conceptual weather model of regional hail and torrential rain (>100mm/3h). According to the500hPa, torrential rain often occurred in three circumstances.40%is influenced by North China cold vortex.36%of them locates at the edge of the subtropical high, and the rest of them are caused by the typhoon trough. The regional hail weather come up most in control of the North China cold vortex (72%), and the rest of them are influenced by west wind trough type.Some parameters in relation to the atmosphere stability, temperature and humid parameter and energy argument have been calculated in the last part. Some results have been obtained, CAPE, SI index, SWEAT index,0-3km vertical wind shear and BLI have important effect on distinguishing the occurrence of severe weather, but they have insufficient difference in discriminating severe weather type.0℃,-20℃height, temperature difference between850hPa and500hPa, precipitabal water vapor, low-lever wind shear, K index, TT index, A index, and LI could distinguish the category of the rainstorm and hailstorm.