通辽市暴雨特征分析及区域性暴雨定量评估方法

基于通辽市 1960—2020 年的日降水量资料,分析暴雨站次及区域性暴雨过程时空变化特征,并利用国家标准 GB-T 42075-2022 对区域性暴雨过程进行定量评估。结果表明:(1)暴雨极值呈明显的南部地区大于北部,暴雨站次分布整体上北部和中西部少,南部和中东部多。年平均暴雨日数 0.8 d。7～8月为发生暴雨主要月份。(2)区域性暴雨过程共45次,年平均 0.7 d,年际变化呈减少趋势。单日区域性暴雨占78%。主要出现在7月下旬达11次。(3)利用国家标准定量评估,得出有 3 次特强区域性暴雨过程,依次为 2017 年 8月3日、1994年7月12～14日、1984年8月10～11日。结合本地情况,定义综合强度Z值在100以上为特强区域性暴雨,Z值在40以上为强区域性暴雨,Z值在30以上为较强区域性暴雨。区域性暴雨等级评估方法适用性较好,利于区域性暴雨过程强度的划分。

Characteristic Analysis of rainstorm and Quantitative Assessment of Regional rainstorm in Tongliao City

Based on the daily precipitation data of Tongliao City from 1960 to 2020, the temporal and spatial variation characteristics of rainstorm stations and regional rainstorm processes are analyzed, and the regional rainstorm processes are quantitatively evaluated using the national standard GB-T 42075-2022.The results indicate that:(1) The extreme value of rainstorm is obviously higher in the south than in the north. The distribution of rainstorm stations is less in the north and central and western regions, and more in the south and central and eastern regions. The annual average number of rainstorm days is 0.8 d. July August is the main month for rainstorm.(2) There are 45 regional rainstorm processes, with an annual average of 0.7 d, and the interannual variation shows a decreasing trend. Single day regional rainstorm accounts for 78%. Mainly occurring 11 times in late July.(3) According to the quantitative assessment of national standards, there were three extremely strong regional rainstorm processes, namely August 3, 2017, July 12-14, 1994, and August 10-11, 1984.Combined with local conditions, it is defined that the comprehensive intensity Z value above 100 is a very strong regional rainstorm, Z value above 40 is a strong regional rainstorm, and Z value above 30 is a strong regional rainstorm. The assessment method of regional rainstorm grade has good applicability, which is conducive to the division of regional rainstorm process intensity.