安徽省近50年雷暴的时空变化特征及影响因素

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

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。

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 thunder- storm 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 thunder- storm 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 distri- bution 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.