2021年6月27日—7月4日桂东北连续暴雨成因分析

Analysis on cause of continuous heavy rain in Northeast Guangxi from June 27 to July 4, 2021

利用常规观测资料、MICAPS及多源融合细网格实况和再分析资料,对2021年6月27日—7月4日桂东北连续强降水过程进行了综合分析。结果表明,桂林市西北部出现连续8d、最大累计雨量达1005mm、资源站24h累计降水突破历史极值的强降水,不仅与稳定的环流形势有关,也与地形的抬升作用密切相关;稳定且强大的副热带高压为连续性强降水提供了背景条件,副热带高压稳定维持在桂林市东南部以及低涡切变的交替影响是暴雨持续的关键;850hPa低空急流脉动以及地形的抬升作用使短时暴雨增幅;强降雨带位于850hPa辐合带和500hPa强上升区附近;强降水由强对流云团持续影响及强降水回波形成的列车效应造成。

Based on conventional observation data, MICAPS and multi-source fusion fine-grid factual and reanalysis data, the continuous heavy precipitation process from June 27 to July 4, 2021 is comprehensively analyzed. The results show that the northwest of Guilin city experienced heavy rainfall for 8 consecutive days,with the maximum accumulated rainfall reaching 1005mm, and the 24-hour accumulated precipitation of Ziyuan station broke through the duration extreme value. It was not only related to the stable circulation situation, but also closely related to the uplift of the terrain. The stable and strong subtropical high provided favorable background conditions for continuous heavy rainfall. The steady maintenance of subtropical high in the southeast of Guilin and the alternating influence of low vortex shear were the key to the continuous heavy rainfall. Besides,the 850hPa low-level jet pulsation and the lifting effect of topography increased the short-time rainstorm. The strong rain belt is therefore located near the 850hPa convergence zone and the 500hPa strong rising zone. The heavy precipitation is also caused by the continuous influence of the strong convective cloud and the train effect formed by the heavy precipitation echoes.