Climatic Change Characteristics of Thunderstorm in Zhangjiakou City

In order to understand the climatic change trend and characteristics of thunderstorm in Zhangjiakou City,and provide climate background basis for the thunder prevention and lightning disaster reduction in the region,observation data of the thunderstorm at Zhangjiakou ground meteorological station from 1960 to 2013 were statistically analyzed by linear fitting,climate trend rate,M-K test,guaranteed rate method and so on. The results showed that the average annual thunderstorm days reached 37. 7 d in Zhangjiakou City from 1960 to 2013,and was in the moderate thunderstorm range. In nearly 54 years,thunderstorm day was reducing at the rate of about 1. 21 d /10 a in the city. There was thunderstorm in other three seasons except winter,and thunderstorm frequently occurred in summer. Summer thunderstorm day was reducing at the rate of about 1. 29 d /10 a,which caused the reduction of the annual one. In summer,thunderstorm day of July reduced most significantly. There were two key points of abrupt reduction,which occurred in 1971 and 1998,on the change of thunderstorm days in Zhangjiakou in recent 54 years. The first thunderstorm date had an advancing trend in recent years,while the final date had not an obvious change. The possibility of thunderstorm was very small from late October to next March in Zhangjiakou City. The first thunderstorm date occurred mostly before middle May,and the period from middle and late May to early and middle September was the high incidence of thunderstorm. The thunderstorm occurred mostly in the NW direction,with the least in E and SE directions,and dissipated mostly in SE direction,with the least in NW and W directions.

Analysis on Climatic and Synoptic Characteristics of Thunderstorm Gale Weather in Jiangsu

By using observation and sounding data at 68 artificial observatories of Jiangsu Province during 2009- 2013,thunderstorm gale weather and its climatic characteristics in Jiangsu were conducted statistics. The characteristics of some instability indexes and strong convection parameters were analyzed,and environmental parameters of dry and wet thunderstorm gales were contrasted. Results showed that thunderstorm gale in Jiangsu had the characteristics of high occurrence frequency,local feature and stronger intensity. It was mostly accompanied by precipitation,and had obvious seasonal and daily change characteristics. Synoptics analysis showed that temperature-humidity profile characteristics before thunderstorm gale appeared in Jiangsu mainly had four types： bell mouth type,inverted V type,dry unstable type and wet unstable type. Before thunderstorm gale occurred,atmospheric instability was stronger,and some strong convection parameters all had certain instructions. But the forecasts of some thunderstorm gale processes were easy to be missed by only considering CAPE. Environmental condition difference of generating dry and wet thunderstorm gale was that instability of dry thunderstorm gale was stronger than that of wet thunderstorm gale. Before dry thunderstorm gale occurred,environmental temperature at middle-low layer was lower; lapse rate was larger; humidity was small. Before wet thunderstorm gale occurred,environmental temperature was higher; lapse rate was small; humidity was large. At dynamic structure,vertical wind shear at 0- 6 km of dry thunderstorm gale was significantly stronger than that of wet thunderstorm gale.