安徽省近50年雷暴的时空变化特征及影响因素

利用安徽省78个气象台站1961～2009年逐日雷暴资料，统计出历年各站雷暴日数并建立时间序列，通过趋势分析、EOF分析、小波分析、MK突变检验等方法对安徽省近50年雷暴的时空变化特征及影响因素进行分析。结果表明：安徽省雷暴日数存在显著的减少趋势；空间分布为南部多于北部，山区多于平原；季节分布为夏季最多，春季次之，秋季相对较少，冬季很少出现雷暴；初雷日期推迟而终雷日期提早，雷暴期有缩短趋势；安徽省所有台站的雷暴日数均在减少，其中江淮之间西南部及皖南南部减少的幅度最大；雷暴日数EOF展开前3个模态累积方差贡献达987%，第一模态为全省一致型，第二模态为南北相反型；雷暴日数存在10~12年和2~3年左右的周期，在1976年存在一次显著突变；雷暴的时空变化与大气环流、纬度、地形、季节等因素有关

SPATIAL-TEMPORAL VARIATION OF THUNDERSTORM AND ITS INFLUENCING FACTORS OVER ANHUI PROVINCE IN RECENT 50 YEARS

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.