汾河流域50年降水量时空变化特征

运用线性倾向估计的方法,利用汾河流域1957~2006年逐月观测的降水资料,分析了汾河流域降水量的时空分布规律和长期变化趋势。结果表明:近50年来,汾河流域降水量年内分配不均、年际变化小,总趋势以21.49mm/10a的变化率减少,特别是20世纪90年代以来降水明显减少,这种减少主要是由夏季降水量减少所引起的,变化率为-9.04mm/10a,而在春、秋两季降水量则呈现出增加的趋势,变化率分别为8.36mm/10a和2.28mm/10a;空间分布表明该区域降水量的地理分布不均,南北梯度大,东西差异小,有阶段性和周期性比较明显等特点。

Spatial and Temporal Variation of Precipitation in Fenhe Valley for 50 Years

On the basis of precipitation database collected by 17 meteorological stations in the Fenhe valley during the period of 1957~2005,spatial and temporal variation of precipitation and changing long-term trend of Fenhe valley were analyzed by using the linear regression.The results showed that the trends of annual precipitations were generally decreased and its gradient was 21.49mm/10a.The precipitation assigned uneven in the year and changed small among years.The decrease in the 1990s was the most remarkable in the recent 50 years.The annual precipitation reduction was mainly caused by the precipitation reduction in summer and its gradient was 9.04 mm/10a.However,the precipitations in spring and autumn was increasing and their gradients were 8.36mm/10a and 2.28mm/10a respectively.The spatial distribution of precipitation was influenced remarkably by terrain and showed obviously the gradualness and the periodicity.There was obvious gradient from north to south,small variance from east to west.