Statistical Characteristics and Variations of Thunderstorm Frequency in South China from 1980 to 2010

Abstract

By using the observed data from 20 weather stations in South China,the characteristics of diurnal,seasonal,multi-year variations and relative atmospheric physical parameters and circulation fields were demonstrated. The results show ed that the thunderstorm frequency peak from afternoon to the evening(9% at 12: 00(UTC,hereafter the same)),and least in the morning(2% at 03: 00). The higher thunderstorm frequency occurred in July and August( 35%),and the low er thunderstorm frequency in December and January( 1%).The annual and summer thunderstorm frequency decreased with a rate of-1% ·(10a)-1and-3. 5% ·(10a)-1from 1980 s to 21 thcentury,yet after 21 thcentury,it has a weak increasing trend. On the whole year,the ratio of thunderstorm precipitation and total precipitation was 48%,but in summer,the value was 64%. The variation of annual(summer) thunderstorm precipitation were relatively similar with annual(summer) thunderstorm frequency,their correlation coefficient was 0. 46(0. 71). In summer,accompany with the variation of thunderstorm frequency,the atmospheric circulation exhibits large-scale abnormally in east Asia. During higher thunderstorm frequency month,the western Pacific subtropical high was abnormally weaker. Meanw hile,there was abnormally ascending flow s in the upper-middle troposphere over the South China. In addition,from the view of thermal instability,the abnormally high total tolals index and abnormally high convective available potential energy index has significant relationship with thunderstorm frequency,their correlation coefficients were 0. 58 and 0. 76. The thunderstorm frequency has statistical relevance with the surface temperature,how ever,it requires substantial investigation to make sure that whether it is a response of thunderstorms thermal and dynamical factor to the global climate change.