洞庭湖流域无雨日数的变化特征研究

Characteristics variation of rainless days in Dongting Lake Basin

利用近34年洞庭湖流域38个气象站点1980~2013年的降水数据资料,采用趋势分析法,M-K突变检验法对洞庭湖流域无雨日数的时间和空间特征进行分析。结果表明：在过去34年,区域内年无雨日数最多的季节为秋季,最少为春季。年无雨日数总体呈上升趋势;从季节无雨日数来看,春季、夏季、秋季呈上升趋势,冬季无雨日数呈下降趋势。突变分析表明：年无雨日数可能在1981年、1991年和2006年发生了突变。无雨日数空间分布明显,流域站点春季无雨日数由西北向东南递减;夏季由东部向西部递减;秋季大致由西北向东南增加;冬季无雨日数以东部站点居多。就各个站点来看,流域站点多年平均无雨日整体呈增加趋势,其中年无雨日数最大值出现在永顺,最小值出现在资兴。

The characteristic variations of rainless days from 1980 to 2013 were based on the precipitation. The precipitation data of 38 meteorological stations in Dongting Lake Basin using linear regression method, Mann-Kendall test method. The results showed that the rainless days were most in autumn and at least in spring. The annual rainless days tended to increase; rainless days in spring, summer and autumn presented an increasing tendency, while it decreased in winter. Resulting from the Mann-Kendall test method, the abrupt change on annual rainless day may occur in 1981, 1991 and 2006. The spatial characteristic distribution presented obviously, the rainless days decreased from northwest to southeast in spring. It decreased from east to west in summer and increased from northwest to southeast. In winter, the rainless day tended to more at east in the Basin. As for the station, the average annual rainless days tended to increase, and the maximum of the rainless station occurred in Yongshun, the minimum occurred in Zixin.