气象2018，Vol.44Issue(4)：485-499,15.DOI:10.7519/j.issn.1000-0526.2018.04.002
2017年广州"5·7"暖区特大暴雨的中尺度系统和可预报性
Analysis of Mesoscale Systems and Predictability of the Torrential Rain Process in Guangzhou on 7 May 2017
摘要
Abstract
Based on the conventional observation data and the Guangzhou Doppler weather radar data,this article analyzed the synoptic background,mesoscale systems and predictability of the torrential rain process which occurred in Guangzhou on 7 May 2017.By contrasting the members of ECMWF ensemble forecast which successfully forecasted the local heavy precipitation on 7 May 2017 with the failed member, key triggering factor affected this process was investigated.The results show that the ambient condition and dynamic forcing were weaker on 7 May 2017.In the context of weak wind field,a convergence line formed between the warm flow from the sea and the cold downslope wind in the front of mountain,combined with the intense temperature gradient,initially triggering the generation of convective storms. Subsequently,the outflow of the preexisting thunderstorms impacted the warm,moist flow at boundary layer,inducing new convergence lines continually.Therefore the weakened storm-cells enhanced again and aroused the second stage of heavy rainfall.The first stages of the local torrential rain on 7 May 2017 was induced by short-lived severe local storm with a meso-vortex evolved from the steady and strong block-shaped echo.The second stage of this torrential rain was caused by long-lived heavy precipitation (HP-type) supercell storm.However,the band echo merging from a mass of new-born convective cells and moving eastward with the short-wave trough was responsible for the third stage of this torrential rain.The radar echo had the low-quality core vertical structure and warm cloud precipitation character during all the three stages.It has turned out that more enhanced temperature gradient and surface wind convergence might be the important triggering factors for local severe precipitation.This finding is based on the mem-ber comparison of ECMWF ensemble forecast that successfully forecasted the local heavy and weak precipi-tation on 7 May 2017.Now,it is still difficult for numerical models to forecast the extremely heavy rains in short lead-time forecast under the condition of warm sector and,especially,the weak wind field.The main method for this is to enhance rainstorm disaster monitoring and early warning.关键词
暖区/特大暴雨/地面辐合/HP型超级单体/可预报性Key words
warm sector/torrential rain/convergence line/HP-type supercell storm/predictability分类
天文与地球科学引用本文复制引用
伍志方,蔡景就,林良勋,胡胜,张华龙,韦凯华..2017年广州"5·7"暖区特大暴雨的中尺度系统和可预报性[J].气象,2018,44(4):485-499,15.基金项目
公益性行业(气象)科研专项(GYHY201506006)、气象预报业务关键技术发展专项[YBGJXM(2017)02-05]、国家科技支撑计划(2015BAK11B01)、广东省科技计划项目(2015A020217008)、中国气象局强对流预报技术专家创新团队和广东省短临监测预警技术创新团队共同资助 （气象）
