华南地区汛期极端降水的概率分布特征

Probability distribution of precipitation extremes during rainingseasons in South China.

中文关键词:  华南地区，极端降水，概率分布，澳大利亚高压，马斯克林高压

英文关键词:South China, Precipitation extremes, Probability distribution, Australian High, Mascarene High

中文摘要:

      利用1960—2005年华南地区71个测站的逐日降水量资料和NCEP/NCAR南半球月平均海平面气压场再分析资料，采用Le Page检验、广义极值分布等统计诊断方法，研究了华南地区近46 a前汛期（4—6月）和后汛期（7—9月）极端降水的时空变化及概率分布特征。并讨论了南半球澳大利亚高压和马斯克林高压强度指数与华南汛期暴雨日数间年代际变化的关系。结果表明：（1）1992年华南地区降水发生了由减少趋势到增多趋势的突变，降水趋势发生突变后前汛期极端降水量和日极端降水强度有所下降，而后汛期则是显著增强。（2）华南汛期年平均日最大降水量、50 a一遇日最大降水量极值和暴雨日数的空间分布特征相似，即前汛期的空间分布自南向北呈现 “低—高—低”的分布趋势，后汛期呈现由沿海到内陆的“高—低”的分布趋势。（3）1992年发生突变后，前、后汛期年平均日最大降水量和年平均暴雨日数显著增加和减少的空间分布基本一致。（4）就年代际变化而言，南半球澳大利亚高压和马斯克林高压的强度变化是华南汛期降水异常的重要气候背景，即当两高压处在同时增强时期时，华南前汛期极端降水处于偏少阶段，后汛期则处于偏多阶段。

英文摘要:

      Based on the daily precipitation data at 71 stations in South China and the NCEP/NCAR reanalysis monthly mean SLP (Sea Level Pressure) data in the Southern Hemisphere during 1960-2005, the probability distribution of precipitation extremes during the rainy seasons (April-June and July-September) in South China was investigated by using statistical methods, such as the Le Page test and the GEV (General Extreme Value) analysis, The influences of the Australian High and the Mascarene High in the southern Hemisphere on the heavy precipitation days of the south china were also examined. The results show that an abrupt change of precipitation trend in South China occurred around 1992, from a descendent trend to an ascending trend. After the abrupt change, precipitation extremes and the daily maximum precipitation both weakened reduced in the first rainy season (April-June) but significantly enhanced in the second rainy season (July-September). The spatial distribution of precipitation extremes in every fifty years exhibited a similar pattern to that of the daily maximum precipitation and the heavy precipitation days, i.e, in the first rainy season it showed “negative-positive-negative”from south to north and in the second rainy season it became “positive-negative”. After 1992，the spatial distribution of the daily maximum precipitation variation were agreed with that of the heavy precipitation days. On the interdecadal time scale, when the Australian High and the Mascarene High were stronger, precipitation extremes would be less than normal in the first rainy season and more than normal in the second rainy season.