暖湿背景下新疆逐时降水变化特征研究

Temporal and spatial distributions of hourly rain intensity under the warm background in Xinjiang

基于新疆16个国家基准站1991-2013年5-9月逐小时的降水观测资料,分析研究了新疆夏半年逐时降水的时空分布和日变化特征。结果表明：新疆小时降雨频数呈现西北多、东南少的特征;4 mm·h^-1以上量级雨强的强降雨高频时段北疆自西向东依次出现在下午、前半夜和后半夜,南疆多出现在夜间;新疆各区域逐时降水频率的日变化特征明显不同,各区域逐时降水分布并不均匀：塔城北部、阿勒泰地区日降水分布呈现双峰型特征,北疆其余地区则是较为一致的单峰型;南疆各区域以双峰型居多。南北疆0.1 mm·h^-1以上、4 mm·h^-1以上量级雨强的出现总频次均呈明显增加趋势,进入21世纪10年代南疆强降雨频次增加更显著。

It is well known that climate changes sometimes may cause natural disasters,especially the disastrous weather days,as downpour,flood,landslide and mudslide,and their derivatives disasters not only have relationship with precipitation,but also,closely with rainfall intensity. In the practice of Xinjiang disaster prevention,it＇s urgent to know the temporal and spatial distributions of precipitation intensity and the maximum of precipitation intensity in different recurrence periods. In this paper,based on the observed hourly precipitation data over 16 national-standard stations during May to September from 1991 to 2013 in Xinjiang,some large-scale,multisites and long-paying observed hourly precipitation data have been used firstly together with the methods of probability distributions,statistical tests,variant difference analysis and extreme value analysis,the temporal and spatial distributions and the diurnal variation of hourly rain in summer in Xinjiang have been analyzed. The results show that the hourly rain presents high frequency in northwest and low frequency in southeast of Xinjiang. The high value center of the frequency with hourly rainfall intensity over 0.1 mm·h^-1or 4 mm·h^-1both in Western Tianshan Mountains. The frequency of heavy rainfall is increasing in places such as Ruoqiang where rains less. The high frequent periods of heavy rainfall,with hourly rainfall intensity over 4 mm·h^-1,are often occurred in the afternoon,and the first and second half of the night in Northern Xinjiang,while it occurs at night in Southern Xinjiang. The hourly rain frequencies share obviously different diurnal variation in all regions of Xinjiang,where the hourly rainfall is not well-distributed. The distribution characteristic of daily rain in Northern Tacheng and Altay Prefecture is bimodal and in the rest regions of Northern Xinjiang is unimodal. Nevertheless,in Southern Xinjiang,most are in bimodal distribution. The total frequency of hourly rainfall intensity larger than 0.1 mm·h-1or4.0 mm·h-1in Northern and Southern Xinjiang both appears to be an evident increase trend,and it would increase more significance in Southern Xinjiang in the 2010 s. The high value region of hourly rainfall intensity occurring once in 50 or 100 years,respectively 45 mm·h-1and 50 mm·h-1,both is in the western Aksu.