西安地区降水时空分布及变化规律分析

Temporal and spatial distribution and long-term variation trend of precipitation in Xi'an

运用非参数检验法(Mann-Kendall)对西安地区7个县区的降水数据(1961-2005年)做了计算分析,探讨了降水时空分布规律。在时间上,从年、季、月三个角度进行了研究,在空间上,分析了整个区域年降水和春、夏、秋、冬四季降水的分布规律,并检验了其变化趋势。结果表明:1961年以来西安地区降水时空分布不均匀,降水主要集中在夏秋季节,5-10月份的降水可占全年降水量的79%,并且年降水有减少的趋势,其中春、秋季节降水减少,尤其以春季最为显著,变化率为-1.98mm/a,夏、冬季降水有增加的趋势。

On the basis of precipitation data collected from seven gauging stations around Xi＇an city during the period of 1961 - 2005, the temporal and spatial distribution of precipitation in Xi＇an region was analyzed. The Mann -Kendall test was applied to analyze annual and seasonal precipitation time series. The temporal distribu- tion included the variations of year, season and month for the whole region. For spatial distribution, the variation of the precipitation of year and season for the seven areas were determined. The results showed that the temporal and spatial distributions of precipitation was uneven and the mean annual precipitation had a decreasing trend from 1961 -2005, which mainly resulted from the variation of precipitation in the spring and autumn, especially in spring, during which the slope was - 1.98mm/a. While in summer and winter, the precipitation exhibited an increasing trend. The rainy season was concentrated in summer and autumn every year, and the total rainfall during the period from May to October occupied 79% of the annual precipitation.