基于高密度观测的兴宁短时强降水特征分析

Characteristics Analysis of Short⁃term Heavy Precipitation in Xingning Based on High⁃density Observation

利用2013—2022年1个兴宁国家气象站和17个区域自动站24小时逐时降水资料,对兴宁市短时强降水的时空分布进行分析。结果表明:(1)兴宁市短时强降水空间分布总体呈现“北多南少”特征,短时强降水年发生频次EOF分析的前5个模态累计方差占86.49%,其中模态1表现为全市一致偏多(或偏少)型,模态2表现为南北反向型。(2)短时强降水多出现在汛期(4—9月);小时雨强主要以20~39.9 mm为主,最大小时雨强103.9 mm/h,且极值多出现在8—9月;日变化中高频时段出现在14:00—20:00,低频时段出现在03:00—06:00。(3)影响极端短时强降水的主要天气分型为西南气流型、热带系统型以及弱冷空气和切变线型。

The spatial and temporal distribution of short⁃term heavy precipitation(to be referred to as"SHP"hereafter)in Xingning was analyzed by using the hourly precipitation data of a national meteorological observation station and 17 regional automatic weather stations in the city in 2013⁃2022.The results are shown as follows.(1)Spatially speaking,the SHP in Xingning is generally distributed more in the north than in the south,and the cumulative variance of the top five modes in the EOF analysis of the annual fre⁃quency of the SHP accounts for 86.49%,with Mode 1 being the uniformly more common(or less common)type in the whole city,and Mode 2 being the reversed north⁃south type.(2)The SHP mostly occurs in the rainy season(April⁃September).The hourly rain intensity is mainly from 20 to 39.9 mm,the maximum hourly rain intensity is 103.9 mm/h,and the extreme value mostly appears in August⁃September.For the diurnal range,the high frequency period occurs at 14:00-20:00,and the low one occurs at 03:00-06:00.(3)The main weather types affecting extreme SHP are the southwest airflow type,tropical system type,weak cold air and shear type.