摘要
本研究利用Tropical Rainfall Measuring Mission(TRMM)卫星数据研究了华南地区1998—2013年暖季(4—9月)极端降水系统(Extreme Precipitation Event,简称EPE)的精细结构和环境特征,并对比分析了非极端降水系统(NonEPE)包括雷暴(Thunderstorm)和未造成极端降水的强对流系统NonEPE_Inten。利用华南地区约1500个站点的小时降水数据,1981—2013年气候统计的99.9^(th)作为极端小时降水阈值。EPE(NonEPE)定义为降水中心强度达到(未达到)极端小时降水阈值且降水面积至少为100 km^(2)的对流系统。结果表明,华南EPE对流核的水平尺度达到了中β尺度(45~50 km),与雷暴尺度相当;大部分EPE发生在组织性强的中尺度对流系统(>100 km)内,NonEPE多数发生在尺度相对较小的对流系统(<100 km)中。卫星微波观测表明EPE含有丰富的冰相粒子,冰相过程显著。EPE与强对流的垂直结构具有显著差异,它们的雷达反射率因子在融化层以下分别增长了6~7 dBZ和2~3 dBZ,表明EPE暖雨(碰并)过程更活跃,其雨滴在暖云中高效增长。EPE的环境特征表现为整层大气相对湿度高,700~925 hPa风切变强,暖云厚度更深厚,但对流有效位能(CAPE)较弱,低层气温较低。
This study investigates the precipitation structures and environmental conditions of Extreme Precipitation Events(EPEs)over South China during the warm season(April-September,1998-2013)using TRMM satellite data.The structure and environmental characteristics of the Non-Extreme Precipitation Events(NonEPEs),including thunderstorm,and the convective NonEPEs(NonEPE_Inten),which lacks extreme precipitation,are compared and analyzed.The hourly extreme precipitation threshold is defined using the 99.9^(th) percentile of hourly precipitation data of about 1500 stations in South China during 1981-2013.EPE(NonEPE)refers a convective system in which the intensity of the precipitation center meets(does not meet)the extreme hourly precipitation threshold,and the precipitation area is at least 100 km^(2).Results indicate that the horizontal scale of EPE over South China exhibits meso-βscale(45-50 km),which is the scale of thunderstorms.Most EPEs occur in organized mesoscale convective systems(horizontal scale>100 km),while NonEPEs primarily occur in relatively small-scale convective systems(horizontal scale<100 km).Satellite microwave observations indicate that EPEs contain abundant ice particles.The vertical structure of EPE is significantly different from that of strong convections.The radar reflectivity of EPE(non-EPE)increases by 6-7 dBZ(2-3 dBZ)below the melt layer,indicating EPE has a more active warm rain or collision-coalescence process with higher raindrop growth efficiency.In terms of environmental conditions,EPE show higher relative humidity,stronger 700-925 hPa wind shear,thicker warm cloud depth,weaker convective effective potential energy(CAPE),and lower low-level temperature.
作者
韦慧华
符娇兰
田志广
陈浩
徐伟新
WEI Huihua;FU Jiaolan;TIAN Zhiguang;CHEN Hao;XU Weixin(School of Atmospheric Sciences,Sun Yat-sen University,Zhuhai,Guangdong 519082,China;National Meteorological Center,China Meteorological Administration,Beijing 100081,China;Hebei Meteorological Administration,Shijiazhuang 050021,China)
出处
《热带气象学报》
北大核心
2025年第4期541-552,共12页
Journal of Tropical Meteorology
基金
国家自然科学基金(42275054)资助。
关键词
极端降水
强对流
中尺度对流
星载降水雷达
extreme precipitation
strong convection
mesoscale convective system
spaceborne precipita‐tion radar
