摘要
利用常规观测、卫星数据及ERA5再分析数据,从动力和热力角度对引发2020年5月24—25日广西北部暴雨过程的低涡发展维持机制进行诊断分析。结果表明:低涡在滇黔桂交界一带生成,随后逐渐发展东移,对流云团及降水落区主要分布在低涡东侧及南侧。涡度方程诊断表明,低涡的发展维持主要受涡度平流项和水平散度项影响。水平风场对涡度的输送使局地涡度减小,水平风场的辐合效应使局地涡度增大。将原始风场分解为地转风和非地转风分量后发现,非地转风分量主导了局地涡度的变化,非地转风水平散度项正贡献最大,扭转项次之,两者是造成低涡发展维持的主要原因。在热力作用方面,低涡发展移动过程对流层中层附近的潜热加热正反馈有利于低层低涡的发展维持。
Based on the conventional observation,satellite data and ERA5 reanalysis data,the development and maintenance mechanism of the vortex that causing regional rainstorm in northern Guangxi during 24-25 May 2020 is analyzed from the dynamic and thermal perspectives.The results show that the vortex occurs firstly at the boundary of Yunnan,Guizhou,and Guangxi,and gradually intensifies and shifts eastward.Convective clouds and precipitation are predominantly observed in the eastern and southern flanks of the vortex.Diagnosis of the vorticity equation reveals the pivotal influence of the vorticity advection term and horizontal divergence term on the evolution and persistence of the vortex.The vorticity transported by the horizontal wind field contributes to the reduction of local vorticity,while the convergence effect acts to amplify it.By decomposing the primary wind field into geostrophic and ageostrophic wind components,the analysis underscores that the changes in local vorticity are predominantly driven by the ageostrophic wind components.Among these components,the horizontal divergence term of the ageostrophic wind yields the most significant positive impact,followed by the torsional term.These factors collectively serve as the primary drivers behind the development and maintenance of vorticity within the system.Moreover,with regard to thermal effects,the study emphasizes the crucial role of positive feedback from latent heating near the mid-level troposphere during the vortex's evolution and movement,facilitating its continued development and sustenance.
作者
覃皓
周云霞
农孟松
黄晴
苏洵
QIN Hao;ZHOU Yunxia;NONG Mengsong;HUANG Qing;SU Xun(Guangxi Meteorological Observatory,Nanning 530022,China)
出处
《沙漠与绿洲气象》
2024年第2期68-75,共8页
Desert and Oasis Meteorology
基金
广西气象科研计划项目(桂气科2021Z03)
广西自然科学基金项目(2022GXNSFBA035565)
广西壮族自治区气象局短时临近天气预报技术创新团队项目。
关键词
低涡
涡度方程
非地转
潜热加热
vortex
vorticity equation
ageostrophic
latent heating
