THE SPATIAL AND TEMPORAL DISTRIBUTION OF CHINESE TORNADOS AND THEIR CHARACTERISTICS ANALYSIS OF ENVIRONMENTAL PHYSICAL VARIATIONS

FENG Jia-wei; MIN Jin-zhong; ZHUANG Xiao-ran

doi:10.16032/j.issn.1004-4965.2017.04.010

Abstract：Using data of Chinese Meteorological Disasters Yearbook for 2004 to 2012 and CFSR reanalysis,this paper analyzes the spatial and temporal distribution characteristics of tornadoes in China,circulation background field and the characteristics of environmental physical variations in three tornado-prone regions,and compares their regional differences.The results showed that tornadoes occurred most frequently in spring and summer,and in the afternoon and at dust.Probabilities of tornado occurrence over plains in Jiangsu and Guangdong are the highest.When tornadoes are approaching,Jiangsu and its adjacent regionsare located before a trough at 500 hPa level,and a 850 hPa southwest jet leads to a strong low-level vertical wind shear;the mean CAPE value of Guangdong and its adjacent regions preceding to tornado events is 997.3 J/kg and the mean 0～1 km helicity value is 91 m2/s2,indicating stratification instability and strong dynamic lifting.Northeast China is controlled by a deep Northeast cold vortex,the moisture content of the whole layer is low,and the mean specific humidity value in the middle and lower atmosphere is lower than 10 g/kg.By comparing the distribution characteristics of the mean environmental physical variations field,it is demonstrated that helicity,vertical wind shear,EHI and STP are good indicators to tornado occurrence.The mean CAPE and helicity values of Northeast Chinaare far lower than those of the Jiangsu and its adjacent regions and Guangdong and its adjacent regions.With higher upper and lower-level lapse rates and strong middle and lower-level vertical wind shear,however,there is also possibility for tornado occurrence.