中国西南地区时雨量分布特征与时月变化

利用2005-2017年夏半年国家大监站的逐小时降水量资料，14个要素被设计来进行多角度分析。多数要素与地形高度有良好的负相关关系。时段雨量最大值主要集中地是四川盆地西部，其次是贵州南部，云南南部边缘地带有少许站点，云贵高原主体及其与青藏高原交接带内没有最大值出现。多个要素在9到12时出现日变化最高峰。月际变化一般在7月出现最大值。随月份推进，强降水区会在贵州西南部、云南南部边缘出现后，跳跃到川渝地区出现。时段累积雨量最大值随时间增加而增加，多个要素的时间增加一倍时雨量增大10%到20%。以小时而言，西南地区降水几率平均为1/10，最多的可以达到1/4，最少的不到1/14。6月份降水时数最多，10月的雨时数仅次于6月，4月最少。连续时段与标准日界时段雨量的显著差异出现在川渝地区；白天12 h降水与夜间12 h降水的显著差异也出现在川渝地区。总体而言，连续时段的累积雨量大于标准日界的相同时间长度的累积雨量，白天降水量大于夜间降水量。

Distribution Characteristics and Variation of Hourly Precipitation in Southwest China

Based on hourly precipitation data during 2005-2017, 14 elements are designed to analyze characteristics of distribution. Most of them, especially the area mean over 3-mm per hour, have a lot to do with the topographic height. The ratio of rain hours over total hours has nothing to do with the height. Maximums for accumulated precipitation over different periods mainly concentrated in west Sichuan Basin, secondly in south Guizhou, thirdly in south Yunnan. There are no this kind of maximum over the Yunnan-Guizhou Plateau. The peaks of daily change for many elements appear in 9 to 12 o’clock in the morning. The peaks for monthly change of elements usually occur in July, sometimes in June and August. Heavy-rain areas firstly appear in southwest Guizhou and south Yunnan, and then suddenly jump to Sichuan Basin. Accumulated rainfalls over different periods increase together with the increase of time. Many ratios between accumulated rainfalls for vary periods are very close, just between 10 to 20 percent. Relative to hour, precipitation probability in southwest China averagely is ten percent. The largest is one fourth, and the smallest is one fourteenth. The probability for rain hours is greatest in June, secondly in October, and smallest in April. Generally, distinct differences between rainfalls in continuous and standard-daily-boundary periods appear in the Sichuan basin, and distinct difference between rainfalls in day and night also appears in this area. Rainfalls in continuous periods are always larger than or equal to that in standard-daily-boundary periods which have the same time length.