Abstract:

This paper counted up the station thunderstorm gust days over the years and analyzed the temporal and spatial distribution characteristics by using 78 meteorological stations daily thunderstorm gust data in Anhui Province from 1971 to 2010.It also analyzed the temporal and spatial variation of thunderstorm gust in recent 40 years in Anhui Province by using MannKendall method,wavelet analysis method,EOF decomposition method and etc.The results show as follows.There was a significant decreasing trend of thunderstorm gust days sum in Anhui Province.The most concentrated period of time for thunderstorm gust was in the summer from June to August,accounting for about 69% of the year.The diurnal variation of thunderstorm gust mainly showed singlepeak structure,peaking in 15〖DK〗∶00 to 16〖DK〗∶00 BT.The spatial distribution characteristics had no obvious relationship with latitude,mainly had relationship with the influence of convective weather system and factors of regional and terrain.Thunderstorm days had a significant mutation at 1987 in Anhui Province.Wavelet analysis showed that there were 10 years and 6—8 years significant oscillation cycle.In the time scale of 10 years,thunderstorm gust days experienced 4 alternating cycles from more to less,multiple thunderstorm gust periods were around 1995 and from 2003 to 2005,and the thunderstorm gust days would remain in the reduced state after 2010.For 10 years the quasiperiodic,oscillation of 10 years was small before 1995,but intense oscillation occurred after 1995.The contribution of the first four modal cumulative variance of EOF decomposition of thunderstorm gust days was up to 61%.The first mode could most reflected the main characteristics of thunderstorm days annual distribution in Anhui Province.The time coefficients of each mode had obvious interdecadal variation