Structural Characteristics of the Evolution of a Stable Low-motion Southwest Vortex and Its Relationship with Heavy Rainfall 

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  • 1. Institute of Plateau MeteorologyChina Meteorological AdministrationCMA),Chengdu 610072SichuanChina
    2. Gaoping Meteorological BureauNanchong 637100SichuanChina
    3. Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of
    Sichuan Province
    Chengdu 610072SichuanChina

Online published: 2025-06-16

Abstract

This paper is mainly about the typical stablelow-motionlong-life warm southwest vortex rainstorm process on July 26-272023. Based on the analytical field data of the Southwest Regional ModelSWCand the precipitation data of weather stationsthe paper studies the evolution of the horizontal and vertical structure of the southwest vortex at different stages of its life cycle and its relationshipin terms of space as well as timewith heavy precipitation. The research results are the following. First of allthere are five distinct stages within the life circle of the Southwest vortex causing the rainstorm on July 262023initialdevelopmentpeakmaintenance and decay. Secondlythe horizontal and vertical structures of the southwest vortex show asymmetric characteristicsand the dynamic and thermal structure of the low vortex differ in different evolution stagesthus affecting differently. In the initial phrasethe release of latent heat of condensation in the convergence uplift enhances the low vortexand relies more on the transformation of the total potential energy to the kinetic energycausing the low vortex to escalate. Since the strong dry cold air moving south weakens the transport of southerly warm humid wind and vaporthe atmospheric Stratified stability increasesand the low vortex attenuates accordingly. Finallythe 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 centerwhile that at the strong stage occurs on the side of the strong warm and wet airflow channelwith 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.

Cite this article

FAN Dian, LU Ping . Structural Characteristics of the Evolution of a Stable Low-motion Southwest Vortex and Its Relationship with Heavy Rainfall [J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00061

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