气象与环境学报2024，Vol.40Issue(5)：1-11,11.DOI:10.3969/j.issn.1673-503X.2024.05.001
广西"6·13"强降水过程低空急流的作用及其日变化成因
The role of low-level jet and its cause of diurnal variation during the"6·13"heavy rainfall process in Guangxi
摘要
Abstract
Based on observation data and ERA5 reanalysis data,an analysis and diagnosis of thes"6·13"heavy rainfall process in Guangxi in 2022 were conducted,with a focus on the role of diurnal variation and its cause of low-level jet.The results show that the heavy rainfall process is jointly influenced by the upper level trough,the low-level shear line and the southwest low-level jet.The low-level jet weakens during the day and significantly strengthens at night,with convective systems continuously developing at the top of the jet and the south of the shear line,resulting in heavy rainfall mainly concentrated at night.The extreme heavy rainfall appears during the merging stage of mesoscale convective cloud clusters,located in the large TBB(Top Blackbody Brightness tem-perature)gradient region.The convergence in the left front of the low-level jet at night and the obstruction of mountain topography together enhance the low-level convergence and promote the development of upward move-ment.The intensification of low-level jet at night causes the intense convergence of warm and cold air in the north-eastern region of Guangxi,resulting in the enhancement of low-level horizontal frontogenesis forcing,which is con-ducive to the maintenance and intensification of precipitation.Under the continuous warm and humid transport of the low-level jet,the unstable structure in the lower atmosphere is significantly enhanced,which provides a favora-ble environment for the development and maintenance of convective systems and heavy rainfall.In addition,the low-level jet promotes the water vapor convergence and uplift in the northeastern region of Guangxi at night,which corresponds well with the heavy rainfall area.The diagnosis of momentum balance shows that inertial oscillation is the main mechanism causing the diurnal variation of low-level jet.The Coriolis force at night dominated the mo-mentum change of the geostrophic wind,which rotates clockwise to form the southwest wind and superimposes with the background wind field to strengthen the low-level jet.The daytime turbulent friction is enhanced and the residual and advection terms jointly dissipate local momentum.关键词
低空急流/锋生强迫/动量收支/惯性振荡Key words
Low-level jet/Frontogenesis force/Momentum balance/Inertial oscillation分类
天文与地球科学引用本文复制引用
覃皓,刘乐,农孟松..广西"6·13"强降水过程低空急流的作用及其日变化成因[J].气象与环境学报,2024,40(5):1-11,11.基金项目
广西自然科学基金项目(2023GXNSFBA026340)和广西气象科研计划创新平台专项(BNCO-K202401)共同资助. （2023GXNSFBA026340）
