Analysis of Climate Characteristics and Radar Echo of Strong Thunderstorm in Hongze Lake Region

By using the thunderstorm data of thirty years during 1980 to 2009,this paper has analyzed the time distribution characteristics and variation regularity of the strong thunderstorm in Hongze Lake region, and classified the synoptic situation of strong thunderstorm days in terms of weather maps during 2005 to 2009.It is found that the average annual strong thunderstorm day is 8.0 d,the main meteorological disasters accompanied by strong thunderstorm are strong wind and heavy rainfall;it is more likely to happen in June to August and most frequently at 4 am to 6 am and 14 pm to 16 pm of a day,which often sustained within 2 hours.The second order moving average(decadal change) goes up at first,and then falls down. The strong thunderstorm forms in four synoptic systems:trough cold front,northern cold vortex,low-level shear (trough) line,and subtropical high;at the same time the southwest jet exists in both low-level and high-level atmosphere, and the Hongze Lake region is in a wet tongue where T—T_d of 850 hPa is no more than—3℃.The main echo features of the strong thunderstorm are as follows;there is a sharp vertical shear before the echoes,and the remaining VIL value at the 35 kg·m~(-2) implicates the appearance of heavy rainfalls;before strong winds,VIL value often declines evidently.And during the rainstorm,its negative lightning concentration region is in good correspondance with the strong radar echoes above 40 dBz.