Abstract:

By using daily thunderstorm data in 78 stations of Anhui Province during 1961～2009,this paper calculated the sum of annual thunderstorm days in every station and established a time series,then analyzed the spatialtemporal variation of thunderstorm and its influencing factors over Anhui Province by trend analysis,EOF,wavelet analysis,MannKendall test and so on.The results showed that:the annual thunderstorm days over Anhui Province presented a significant decreasing tendency;thunderstorm days in the south overwhelmed that in the north and that in mountain overwhelmed in plain;the seasonal distribution proved that thunderstorm days in summer ranked the first,in spring the second,in autumn the third and in winter the last;the thunderstorm also showed a tendency to begin later and end earlier,thus the thunderstorm period shortened;the thunderstorm days of all stations in Anhui Province decreased,and that of those stations in the southwest of the YangtzeHuaihe area and the south part of Anhui Province decreased most sharply.The cumulative percent variance of the EOF’s first three modes reached 987%.The value of first mode of EOF was consistent everywhere,meanwhile the second mode of EOF indicated that the distribution of thunderstorm days between south and north was contrary.Thunderstorm days which mutated once around 1976 had two main periods,around 10~12 years and 2,3 years.The spatialtemporal variation of thunderstorm was closely related to those factors such as atmospheric general circulation,latitude,terrain,season,etc