湖南西南急流型暖区暴雨特征分析

Analysis of the Southwest Jet Stream Type Warm-sector Rainstorm in Hunan Province

摘要:

使用常规观测、ERA5再分析及多普勒天气雷达风廓线等资料，对湖南5次西南急流型暖区暴雨过程进行分析，初步建立了该类暴雨天气学概念模型，并对发生条件、急流脉动进行分析。结果表明：暴雨区有孟加拉湾和南海的两支水汽通道，水汽输送集中在850 hPa附近；850 hPa西南气流加强加剧了“上冷下暖”层结，800 hPa到1000 hPa垂直风切变在强降水发生发展过程中增强。大气层结处于中度不稳定状态；中等偏弱的对流有效位能、一定的对流抑制也会出现暴雨；暴雨发生前1～2 h，急流脉动向上扩展；1.0～3.4 km高度急流风速大小、厚度和降水有一定关系。

Abstract:

Based on conventional observation data, ERA5 reanalysis data, wind profile of Doppler weather radar data, five southwest jet stream type warm-sector rainstorms were analyzed, and a conceptual model of this kind rainstorm is preliminarily established. The occurrence conditions and jet stream pulses are also analyzed. The results showed that: The rainstorm has two vapor transport channels of Bay of Bengal and South China Sea, and the main water vapor transport altitude is around 850 hPa; The strengthened 850 hPa southwesterly jet intensified the "upper cool and lower warm" stratification. Vertical wind shear between 800 hPa and 1000 hPa shows enhanced features when the rainstorm occurred and developed. The atmosphere is moderately unstable; Moderate to weak Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) would also lead to rainstorms. 1 to 2 hours before the rainstorm, the jet stream pulses spread upward. The wind speed and thickness of jet stream at an altitude of 1.0 to 3.4 km had a certain relationship with precipitation.