一次稳定少动型西南涡演变的结构特征及其与暴雨的关系
网络出版日期: 2025-06-16
基金资助
国家自然科学基金项目(U2242202);科技部国家重点研发计划项目(2022YFC3003902);四川省自然科学基金项目
(2025ZNSFSC0334);四川省中央引导地方科技发展项目(2024ZYD0175)
Structural Characteristics of the Evolution of a Stable Low-motion Southwest Vortex and Its Relationship with Heavy Rainfall
Online published: 2025-06-16
基于 2023 年 7 月 26-27 日一次典型的稳定少动、长生命史暖性西南涡暴雨过程,采用西南区域数值天气预报业务模式(SWC)分析场资料(同化了西南涡科学试验获取的加密探空观测资料)、台站降水数据,系统研究了西南涡不同生命阶段水平和垂直结构的演变状况及其与强降水的时空配置关系。研究表明:(1)影响“2023·07·26”暴雨天气过程的西南涡生命史呈现显著的阶段性特征,可划分为初生期、发展期、鼎盛期、维持期和衰减期 5 个演变阶段。(2)西南涡的水平与垂直结构均呈现非对称性特征,各演变阶段的动力-热力结构存在显著差异:初生期主要通过辐合抬升引发的凝结潜热释放促进低涡增强,其发展主要依赖于全位能向动能的转换机制;当西南涡中尺度系统发展至强盛阶段后,南下的深厚干冷空气致使偏南暖湿气流及水汽输送减弱,大气层结趋于稳定,使得西南涡由盛转衰,进入衰减期。(3)热力-动力的协同作用是本次暖性西南涡降水的主要成因。具体表现为:西南涡发展前期的降水主要发生在涡心周边暖湿区,而强盛期降水则集中于强暖湿气流通道一侧;降水强度与西南涡强度呈现显著的一致性,假相当位温和低层辐合对西南涡降水落区和强度具有重要指示意义。
范 典, 卢 萍 . 一次稳定少动型西南涡演变的结构特征及其与暴雨的关系[J]. 高原气象, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00061
This paper is mainly about the typical stable,low-motion,long-life warm southwest vortex rainstorm process on July 26-27,2023. Based on the analytical field data of the Southwest Regional Model(SWC)and the precipitation data of weather stations,the paper studies the evolution of the horizontal and vertical structure of the southwest vortex at different stages of its life cycle and its relationship,in terms of space as well as time, with heavy precipitation. The research results are the following. First of all,there are five distinct stages within the life circle of the Southwest vortex causing the rainstorm on July 26,2023:initial,development,peak,maintenance and decay. Secondly,the horizontal and vertical structures of the southwest vortex show asymmetric characteristics,and the dynamic and thermal structure of the low vortex differ in different evolution stages,thus affecting differently. In the initial phrase,the release of latent heat of condensation in the convergence uplift enhances the low vortex,and relies more on the transformation of the total potential energy to the kinetic energy, causing the low vortex to escalate. Since the strong dry cold air moving south weakens the transport of southerly warm humid wind and vapor,the atmospheric Stratified stability increases,and the low vortex attenuates accordingly. Finally,the synergistic effect of thermodynamic and dynamic forces is the main cause of the warm vortex rainstorm. The precipitation at the early stage of vortex development occurs in the warm and wet area around the vortex center,while that at the strong stage occurs on the side of the strong warm and wet airflow channel,with the intensity of precipitation corresponding well with that of vortex. Pseudoequivalent potential temperature and convergence are the key parameters indicating the precipitation area and intensity of the southwest vortex.
Key words:
southwest vortex; stable; structure characteristics; rainstorm
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