黔东南地区各季节极端干期日数的时空分布特征

Temporal and Spatial Characteristics of Extreme Dry Spell in Each Season in Southeast Guizhou

利用1961—2009年黔东南地区16个地面气象站的逐日降水资料,分别统计了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、Mann-Kendall突变检验和线性倾向估计等方法,分析了各季节极端干期日数的空间结构和时间演变规律。结果表明,黔东南地区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;夏季黔东南北部的极端干期日数多,春、秋季南部多,冬季南、北部多,西部四季相对较少,年内非均匀性特征显著。在大尺度天气系统控制下,四季极端干期日数事件的步调基本一致,黔东南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49年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、冬季极端干期日数均呈显著的增多趋势,而夏季变化的特征不明显。

The spatial and temporal characteristics of extreme dry spell are analyzed using the daily precipitation data at 16 stations in Southeast Guizhou from 1961 to 2009.Using EOF,Mann-Kendall catastorophe test,linear trend estimate and others,the maximum continuous rainless days（daily rainfall less than 0.1 mm） of each season are analyzed.The results show that the spatial and temporal variation characteristics of the extreme dry spell in each season of Southeast Guizhou have a great difference,the most days of extreme dry spell taken place in autumn,the least days,in spring,and there is the non-uniformity characteristic in a year.Under the control of large-scale weather system,the extreme dry spell of each season had the same frequency,but it is abnormal high in east central of Southeast Guizhou,the influence of the weather systems in different seasons on the sub-region in Southeast Guizhou is of significant localization and stage.After 21st century,the extreme dry spell appears the increasing trend in spring,autumn and winter,but not obvious in summer.