Characteristics of Spatial-Temporal Distribution and Storm Morphologies of Tornadoes in Jiangsu,China

Based on the climate impact assessment documents, significant weather reports, tornado disaster records of Jiangsu civil affairs department and other relevant data from 2006 to 2018 in China , spatial- temporal distribution, strength distribution, weather background and storm morphology characteristics of Jiangsu tornadoes are analyzed, according to the “Enhanced Fujita Scale”. The main results show that there are 41 tornadoes recorded in 27 tornadic days during the 13 year period from 2006 to 2018, with an average annual tornado of 3.2 times. Among them, the most frequent tornado events occurred at EF2 level, accounting for 39%, while the EF4 tornado was only recorded once, which was "6.23" Funing strong tornado. Since the 21st century, there has been no record of extreme Tornado Events of EF5 in Jiangsu Province, while the weak tornadoes of EF0 and EF1 are likely to be ignored due to the weak disaster, and their statistical results may be significantly underestimated. Tornadoes mainly occur in the eastern coastal area, the central coastal area and the western area of the north of the Huaihe River. Compared with the past, the high-risk center of tornado in Central Jiangsu has a trend of moving southward, while the high-risk center in the eastern coastal area shows a feature of northward movement. Yancheng, Xuzhou and Yangzhou are the high frequency cities of tornado in turn, while There is no tornado happened in Suqian, Lianyungang, Changzhou and Zhenjiang in recent years. Most of tornadoes occur in spring and summer, 90% of which are happened in July and August. The beginning of tornadoes is from 10:00 to 20:00 local time, and the peak frequency of tornado genesis in the diurnal variation is between 15:00 and 20:00. From 2006-2018, no EF5 tornado event has been recorded in Jiangsu, and the ratio of EF2 events and EF3 or above events is about 4:1. About 50% of the tornadoes occur during the Meiyu period, while 27% of them are typhoon tornadoes. Yancheng is the highest incidence area of tornadoes in Meiyu period, and Yangzhou-Taizhou is the area with high incidence of tornadoes in Mid-summer. There is no obvious high-risk area of typhoon tornadoes in Jiangsu. More than 50% of tornadoes in Jiangsu are generated in supercell mesocyclone embedded in cluster convective morphology, and about 30% of tornadoes are produced in the QLCSs convective morphology. Contrast to high frequency of tornadoes produced by the discrete cells in the United States, the possibility of tornadoes generated from discrete cells in East China (mainly in Jiangsu Province) is the lowest, and only two tornadoes (less than 5%) were generated in discrete cells in the past 13 years .