基于多源观测资料的一次湖州暖区短时强降水过程分析

Analysis of a Warm-Sector Short-Time Heavy Rain Event in Huzhou Based on Multi-Source Observational Data

摘要: 本文利用常规地面和高空观测资料、卫星云图及多波段天气雷达等资料，对2024年夏季湖州一次暖区局地短时强降水过程进行了分析。结果表明：本次强降水发生在高空冷涡槽前暖区、副高边缘的弱天气尺度强迫背景下，异常充沛的水汽和极高的不稳定能量为强降水提供了极有利的环境条件。边界层辐合线与地形抬升是触发对流的主要机制，阵风锋与湖风锋有效促进了长兴至吴兴平原地区的单体发展，而低层切变线的维持以及弱环境风的共同作用则导致了风暴在安吉西南山区长时间滞留，最终引发了局地暴雨。对造成长兴徐家浜站极端雨强的风暴进一步分析发现，其低层存在小尺度涡旋，且上升与下沉气流呈倾斜配置，使风暴得以持续增强。同时，深厚的暖云层、较低的回波质心结构以及较高的Z_DR和K_DP值，均指示了高浓度大雨滴导致的高降水效率。对于此类弱强迫背景下的暖区暴雨，强化卫星、雷达等多源资料对中小尺度系统的监测分析，是提升预警提前量的关键。

Abstract: Utilizing conventional observations, satellite and multi-band radar data, this study analyzes a localized short-time heavy rain event in the warm sector over Huzhou during the summer of 2024. The result indicates that the heavy rain occurred in the warm sector ahead of an upper-level cold-vortex trough and on the edge of the subtropical high under a background of weak synoptic-scale forcing, with abundant moisture and extremely high instability, which provided highly favorable environmental conditions for the extreme precipitation. Boundary-layer convergence and orographic lifting were the primary mechanisms triggering convection. Gust fronts and lake-breeze fronts effectively promoted the development of convective cells over the Changxing-Wuxing, whereas the maintenance of a low-level shear line, combined with weak environmental winds, caused the storms to remain over the southwestern mountainous areas of Anji for a long time, ultimately resulting in localized torrential rain. Further analysis of the storm responsible for the extreme rainfall rate at the Xujiabangcun station in Changxing revealed the presence of a small-scale vortex in the lower levels, along with a tilted configuration of updrafts and downdrafts, which facilitated the storm’s continuous intensification. Meanwhile, a deep warm-cloud layer, a relatively low echo centroid, and high values of both differential reflectivity (Z_DR) and specific differential phase (K_DP) collectively indicated high precipitation efficiency driven by high concentrations of large raindrops. For warm-sector heavy rain under weak synoptic forcing, enhancing the monitoring and analysis of meso- and small-scale systems by multi-source data, such as satellites and radars, is crucial for extending warning lead time.