中国短时强降雨对暴雨的贡献特征

Contribution of Short-Duration Heavy Rainfall to Rainstorm in China

中国暖季暴雨有显著的对流性特征,但尚不明确对流导致的短时强降雨对不同等级暴雨的贡献程度。利用1951—2019年的逐时降水资料,统计分析了中国两种强度的短时强降雨(小时雨量≥20 mm和小时雨量≥50 mm,分别简称为HR20和HR50)和不同等级暴雨之间的关系,得到了两类短时强降雨对不同等级暴雨的贡献特征。结果显示,短时强降雨发生频率高的暴雨分布区域与暴雨日数多的区域并不一致,在华北南部到黄淮地区和西南地区到华南地区短时强降雨对暴雨的影响最为显著,其超过50%的暴雨中伴随HR20,华北南部和华南中部地区暴雨中发生短时强降雨的占比超过了70%;随着暴雨等级的提升,伴随短时强降雨的比例逐渐增大,尤其HR50的占比增加显著,超60%的特大暴雨中伴有HR50,表明暴雨越强,其对流性越强。在华北南部到黄淮地区、西南地区东部和华南地区,短时强降雨雨量对暴雨雨量的贡献也最大,且随着暴雨等级的提升,这些地区短时强降雨雨量在暴雨总雨量中的占比呈显著增长的趋势,HR50的贡献增幅超过100%;而江淮、江南等地区短时强降雨雨量的贡献较小,随暴雨强度等级的增强其增大程度也相对不明显。此外,伴随有HR20的暴雨、大暴雨平均日雨量较无短时强降雨的暴雨平均日雨量分别多20%和40%以上,进一步印证了中国暴雨对流性强的特点。

The convective characteristics of rainstorms in China are considerable,but the statistical relationship between rainstorms and short-duration heavy rainfall,which is one of the severe convective weather,remains unclear.The characteristics of the contribution of two types of short-duration heavy rainfall(hourly rainfall≥20 mm and hourly rainfall≥50 mm,referred to as HR20 and HR50,respectively)to different intensities of rainstorms are obtained by analyzing the hourly rainfall data collected during 1951-2019.The results show that the area of rainstorm with high frequency of short-duration heavy rainfall is not consistent with the area of high frequency days of rainstorms.Short-duration heavy rainfall has the most significant impact on rainstorms over the south part of North China,the Huanghuai Area and the Southwest to South China,where HR20 accounts for more than 50%of the rainstorm days.The south part of North China and the central part of South China have more than 70%,which is the highest.Furthermore,the proportion of short-duration heavy rainfall gradually increases as the intensity of rainstorms enhances,especially the HR50 has increased significantly.More than 60%of the extreme torrential rain days are accompanied by HR50,indicating that the more intense the rainstorm,the more significant the convection.The total precipitation amounts produced by short-duration heavy rainfall contribute most to the rainstorm over regions such as the south part of North China,Huanghuai Area,the east part of Southwest China and South China.The contribution of the short-duration heavy rainfall also increases significantly as the rainstorm intensity enhances,especially that of HR50 increased by more than 100%.In areas such as Jianghuai Area and Jiangnan,the contribution of the short-duration heavy rainfall is smaller,and its increase is relatively insignificant with the increase of the intensity of the rainstorm.In addition,when there is a short-duration heavy rainfall(HR20),the amounts of torrential rain and sever torrential rain increase by an average of 20%and 40%respectively compared to those with no short-duration heavy rainfall accompanied.This further demonstrates the convective characteristics of rainstorms in China.