桂北一次极端强降雨过程宏微观物理特征分析

Analysis on macro-microscopic physical characteristics of an extreme rainfall process in northern Guangxi

利用环江站降水现象仪雨滴谱资料,结合雷达资料、全球再分析资料(FNL资料),分析了桂北地区2022年6月20日“龙舟水”极端强降雨过程的宏微观物理特征。结果表明,此次过程受短波槽和西南急流影响,桂北地区水汽条件和动力条件较好,深厚湿对流发生发展条件有利,“列车效应”导致环江站短时强降水持续出现;雨强与雨滴直径、雨滴数浓度有较好的对应关系,强降雨时段比弱降雨时段具有更大的雨滴直径和更高的雨滴数浓度;不同降雨时段平均谱均呈单峰结构,数浓度峰值均位于0.7 mm粒径附近。

Based on the raindrop spectrum observation collected by the precipitation phenomenometer of Huanjiang station,combined with the radar data and NCEP/NCAR-FNL reanalysis data,the macro-microscopic physical characteristics of an extreme dragon-boat rainfall process in northern Guangxi on June 20,2022,are analyzed.Results show that the process is caused by a short-wave trough and the southwest jet,which can provide adequate moisture conditions and dynamic conditions in northern Guangxi,in favor of the development of deep moist convection,and the training effect leads to the continuous occurrence of short-term heavy rainfall at Huanjiang station.There is good correspondence between the rainfall intensity and the raindrop particle size and raindrop number concentration.Compared with the weak rainfall process,the heavy rainfall process has a larger raindrop particle size and higher raindrop number concentration.The average spectra of the different rainfall periods show a unimodal structure,with the peak values of number concentration located near the particle size of 0.7mm.