Climatic Characteristics Of Thunderstorm In HUBEI And Related Circulation Variations Background Analysis

The thunderstorm climatic characteristic and spatial anomaly modes of thunderstorm in HuBei province and the relation between large scale circulation in middle and high latitude and vaporinflow flux are analysed in emphasis on the basis of the basal climatic characteranalysis of thunderstorm in HuBei province, by using the thunderstorm observation data of 19 weather station from 1971 to 2010 in HuBei and the NCEP/NCAR reanalysis data. In order to predict the trend of thunderstorms, the grey-BP combined model is built. The main resultsare as follows:(1) The thunderstorm days in Hubei is between 21 and 49. The average number is 35. The max number is 73. The min number is 8. thunderstorm days decrease 2-3 days every ten years. The average thunderstorm day appear at March 27. The first thunderstorm day appear at January 1. The average thunderstorm day disappea at October 6.The Last thunderstorm day appear at december 31. The average first thunderstorm day postpones.The average last thunderstorm day is earlier. Seasonal change characteristic of thunderstorm day is extremely obvious in HuBei province.The thunderstorm mainly occurs in July to September. July is the month with the highest probability of thunderstorm day. The thunderstorm mainly occurs between 20-22.(2) The result of MORLET wave analysis shows that:There are 2years short cyclicality and 11 yearslong cyclicality. The cyclicality changed in 1991. There are 4 years short cyclicality and 7 years long cyclicality between 1991 and 1996. There are 2years short cyclicality and 11 yearslong cyclicality between 1996 and 2010.(3)The thunderstorm days are non-uniform distributionin Hubei. There are more thunderstorm days in Southwest and east. There are more thunderstorm days in moutain than plain.(4)The result of EOF analysis shows that:In the recent forty years, the accordant anomaly is the most important mode of spatial anomaly in HuBei and the antiphase change between southern and northern part of HuBei is also the significant mode.Against the summer thunderstorm anomaly, HuBei province could be partition off to two parts.(5) The vaporin of HuBei come from East Area close to sea. Thunderstorm day anomaly is associated directly with the South vaporinflow flux. There are more thunderstorm days if the South vaporinflow flux are powerful and the position trend to west. The SST of indian ocean and Pacific Ocean are obvious opposite in unusual years. The SST of indian ocean is low. And The SST of Pacific ocean is high in years of more thunderstorm days. The Situation is opposite in the years of less thunderstorm days.(6)In order to predict the trend of thunderstorms, the grey-BP combined model is built. It can predict the next year of thunderstorms occurring frequently.