Dynamic and Thermal Diagnosis of a Warm-Sector Rainstorm During Dragon-Boat Water Period in Guangxi
Qin Hao
Qiu Zi
Huang Minghua
Zhu Liyun
Abstract：Northeast Guangxi suffered a warm-sector rainstorm process during 3-4 June 2022,fea-tured with intensive rainfall and large accumulated rainfall amount,causing flooding and landslide and other secondary disasters.To enrich the understanding of the mechanism of warm-sector rainstorm of Guangxi and provide reference for forecasting services,the dynamic and thermal processes of the warm-sector rainstorm are diagnosed and analyzed based on multi-source data as well as the kinetic energy equation and stratified stability tendency equation.The results show that the divergence in the east side of the South Asia high,the maintenance of mid-level trough and low-level vortex provided a favorable back-ground for the torrential rainfall.The strong warm-humid southwest monsoon provided sufficient water va-por for the occurrence and development of the torrential rainfall.The quasi-stationary meso-α-scale con-vective system and train effect caused the local accumulation of heavy precipitation,which was mainly lo-cated in the large TBB gradient region.The positive vorticity zone on the left of 850 hPa jet coincided with the exit zone of 925 hPa jet and the mountain terrain barrier provided dynamic conditions for the de-velopment of the severe precipitation.The increase of local kinetic energy caused by the decrease of geo-potential height from south to north along with southerly wind was the main cause for the development of low-level jet at night.On the one hand,the development of low-level jet enhanced the low-level conver-gence and promoted the development of ascending motion.On the other hand,the pattern of low-level jet with southerly flow and the θse isoline formed local frontogenesis forcing,conducive to triggering and strengthening the maintenance of torrential rain.The whole process was accompanied by significant low-level convective instability,and the unstable stratification in the early stage of precipitation was jointly maintained by horizontal advection term and potential divergence term.In the heaviest rainfall stage,the strong warm-humid air transport and the upward motion made the convective instability over 900-700 hPa develop continuously,and the potential divergence term promoted the instability near the 925 hPa bound-ary layer.
Keywords：warm-sector rainstormlow-level jetkinetic energyfrontogenesis forcingstratifica-tion stability tendency
Publication Date：2025-11-30
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：10( 1-10 )