近51年鄂西山地降水变化特征及突变分析

利用线性趋势分析、累积距平、Mann-Kendall突变检验和Morlet小波分析法,以地处鄂西山区腹地的宣恩为例,对1959～2009年的月、季、年降水量、降雨日数和极端降水事件进行了综合分析,探讨了鄂西山地近51年的降水量的气候变化特征、降水的突变时间和周期振荡。结果表明,鄂西山区年降水量呈下降趋势,降水倾向率为-27.4 mm/10a,春、秋季降雨量呈下降趋势,尤其秋季以-30.99mm/10a的减少趋势最为显著,夏、冬季呈上升趋势。强降水日数随着年代变化呈减少趋势,极端降雨事件平均每年不足4 d,以-0.033 d/10a的趋势减少。年降水在2008年发生了突变,春、夏、秋降水均有明显的突变现象,降水突变时间分别为1966、1982和1959年。多时间尺度特征主要表现为1～2 a、7～8 a的年际尺度和18 a的年代际尺度的显著变化周期,从18 a左右时间尺度上存在的周期变化看,鄂西山区的降水量会逐渐减少,预计未来可能进入一个相对少雨期。

Analysis on Precipitation Variation and Abrupt Change in Western Hubei Mountain during Recent 51 Years

Based on the linear trend analysis,cumulative anomalies,Mann-Kendall test and Morlet wavelet analysis,the monthly,seasonal and annual precipitation,rainfall days and extreme rainfall in Xuan’en were comprehensively analyzed from 1959 to 2009,the change features,abrupt change time and periodic oscillation of precipitation in West Hubei mountain during recent 51 years were discussed.The results showed that the annual precipitation in Western Hubei mountain decreased at a climatic tendency of-27.4 mm/10a from 1959 to 2009,which was mainly resulted from the reduction of precipitation in spring and autumn,especially in autumn,during which the climatic tendency was-30.99 mm/10a,while in summer and winter,the precipitation exhibited an increasing trend.The days of heavy rain decreased from 1959 to 2009.The extreme precipitation events decreased at a climatic tendency of-0.033 d/10a,which occurred less than 4 days in a year.The abrupt change of precipitation occurred significantly in the whole year of 2008,the spring of 1966,the summer of 1982 and the fall of 1959,The characteristics of multi-time scales indicated that interdecadal scale were around 18 years,interannual time scale were 1-2 years and 7-8 years.From the interdecadal scale,we found that the annual precipitation in Western Hubei mountain would decrease gradually and switch to a dry period in the near future.