1961-2005年宁夏极端降水事件变化趋势分析

 利用1961-2005年宁夏逐日降水量资料，将降水量划分为9个级别，分析了宁夏45 a来各级别降水日数的变化趋势。结果表明：年降水量以平均3.6 mm/10 a的速率减少；近15 a来，冬、春季降水量明显减少，夏、秋季10.0 mm以下降水日数明显减少，25.0 mm以上降水日数明显增加。以1986年为界的气候变暖前后25.1～50.0 mm级别的降水日数夏季和年增加的显著性概率分别达到了5%和1%，降水频率分布呈现向高级别降水量增加的变化趋势。

Trends of Extreme Precipitation Events in Ningxia During 1961-2005

Trends in frequencies of daily precipitation at nine different levels over the last 45 years have been analyzed in this article, using the daily precipitation data from 1961 to 2005 in Ningxia. It has been found that the annual precipitation decreased at a mean rate of 3.6 mm/10 a. In the recent 15 years, precipitation obviously decreased in winter and spring; in summer and autumn, days of precipitation below 10.0 mm obviously decreased, but days of precipitation over 25.0 mm significantly increased. Differences in summer and yearly days of precipitation in 25.1-50.0 mm before and after 1986 were statistically significant at 5% and 1% level, respectively. The extreme trends of precipitation are obvious in Ningxia.