黔东南地区各季节极端干期的变化特征分析

Analysis on Variation Characteristics of Extreme Dry Spells in Different Seasons in Southeast Guizhou Province

利用贵州省黔东南地区16个地面气象观测站1961-2009年逐日降水资料,分别统计四季最大连续无雨日数(日降水量<0.1mm)的时间序列,采用正交函数分解(EOF)、Mann-Kendall突变检验、线性倾向估计等方法,分析各季极端干期日数的空间结构和时间演变规律。结果表明:黔东南各季节极端干期日数的时空分布存在较大差异,极端干期日数最多出现在秋季,最少是春季,夏季北部多,春、秋季南部多,冬季南北部多,西部四季相对较少,年内非均匀性特征非常显著;在大尺度天气系统控制下,各季节极端干期日数事件的步调基本一致,而中东部发生异常的频次较高,不同季节的天气系统对黔东南各区域的影响具有明显的局地性和阶段性;近49a中各季节出现极端干期日数典型多的年份比典型少的年份多;进入21世纪以后,春、秋、冬季的极端干期日数均表现为显著的增多趋势,而夏季的变化不明显。

The spatial and seasonal distribution characteristics of extreme dry spells were analyzed by using daily precipitation data of 16 stations in southeast Guizhou province,China,from 1961 to 2009,using EOF,Mann-Kendall catastorophe test,linear trend estimate etc.to analyze the maximum number of continuous rainless days（days with 0.1mm rainfall） of each season.The results showed that the spatial and temporal variation characteristics of the extremely dry spells in each season of southeast Guizhou had great differences between years and regions.Autumn had the largest number of days of extreme dry spells,while spring had the smallest ones.In the first decade of the 21th century,there were trends of increase of dry spells in all seasons,only the increase in summer was not statistically significant.