On the Diurnal Cycle of Heavy Rainfall over the Sichuan Basin during 10–18 August 2020

查看全文 作　　者：Rudi [1]XIA;Yali [1]LUO;Da-Lin [1,2]ZHANG;Mingxin [1]LI;Xinghua [1]BAO;Jisong [1]SUN

机构地区：[1]State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China;[2]Department of Atmospheric and Oceanic Science,University of Maryland,College Park,College Park,Maryland 20742,USA

出　　处：《Advances in Atmospheric Sciences》索引2021年第38卷第12期,共18页

基　　金：This study was supported by the National Natural Science Foundation of China(Grant Nos.41775050,91937301,41775002,42005008);the Science Development Fund of Chinese of Academy of Meteorological Sciences(2020KJ022). 摘　　要：A sustained heavy rainfall event occurred over the Sichuan basin in southwest China during 10–18 August 2020,showing pronounced diurnal rainfall variations with nighttime peak and afternoon minimum values,except on the first day.Results show that the westward extension of the anomalously strong western Pacific subtropical high was conducive to the maintenance of a southerly low-level jet(LLJ)in and to the southeast of the basin,which favored continuous water vapor transport and abnormally high precipitable water in the basin.The diurnal cycle of rainfall over the basin was closely related to the periodic oscillation of the LLJ in both wind speed and direction that was caused by the combination of inertial oscillation and terrain thermal forcing.The nocturnally enhanced rainfall was produced by moist convection mostly initiated during the evening hours over the southwest part of the basin where high convective available potential energy with moister near-surface moist air was present.The convective initiation took place as cold air from either previous precipitating clouds from the western Sichuan Plateau or a larger-scale northerly flow met a warm and humid current from the south.It was the slantwise lifting of the warm,moist airflow above the cold air,often facilitated by southwest vortices and quasi-geostrophic ascent,that released the convective instability and produced heavy rainfall. 关键词：diurnal cycle heavy rainfall low-level jet inertial oscillation TERRAIN Sichuan basin

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On the Diurnal Cycle of Heavy Rainfall over the Sichuan Basin during 10–18 August 2020

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