近11年广州南沙区短时强降水的特征分析

Characteristics Analysis of Short-term Heavy Precipitation in Nansha.Guangzhou for the Past 11 Years

利用2012—2022年广州南沙区自动气象站逐时降水量观测资料,分析近11 a南沙区短时强降水的时空分布特征。结果表明:近11 a南沙区年平均短时强降水日数为66 d,以局地和区域性短时强降水为主;强降水量级以20~40 mm/h为主,雨强≥50 mm/h的致灾性短时强降水发生次数呈波动增长趋势,极端的短时强降水最易发生在前汛期季风爆发期5月。雨强≥20 mm/h强降水发生日数最多的是7—8月,雨强≥50 mm/h强降水在5和8月发生最频繁。雨强≥20 mm/h和≥50 mm/h强降水具有相似的日变化,即一天当中从午夜到傍晚,两者的发生频次都呈现出波动上升的特征,最易发时段都是午后到傍晚。短时强降水空间分布不均匀,雨强≥20 mm/h和雨强≥50 mm/h强降水都有南北两个显著的高发区,两者高发区范围不同,但高发中心相同,位于北部榄核镇和南部珠江街、龙穴街和万顷沙北部区域。

The spatial and temporal distribution characteristics of short-term heavy precipitation(to be referred to as"SHP"hereafter)in Nansha,Guangzhou in 2012 to 2022 were analyzed by using the hourly precipitation data of automatic weather stations of the district in the past 11 years.The results are shown as follows.In the 11 years studied,the annual average number of SHP days in the district is 66 d,mainly with local and regional SHP.The strong precipitation level is mainly 20-40 mm/h.The occurrence of disaster-causing SHP with tlie rain intensity 5:50 mm/h shows a fluctuating growth trend.Extreme SHP is most likely to occur in May,which is associated with the annually first rainy season and monsoon outbreak.For heavy rainfall at the level of 20 mm/h,it has lire most rain days in July and August,and for heavy rainfall at tire level of 50 mm/h,it occurs most frequently in May and August.Both of the rainfall had similar diurnal change,i.e.,from midnight to the evening during the course of the day,both of them increase in fluctuation and are most likely to occur from post-midday to the evening.The SHP has uneven spatial distribution with both of the rainfall having two significant areas of frequent occurrence in the north and south.Although they differ in the area they cover,they have identical cores of frequent occurrence,in Lanhe Town for the northern part of Nanshan and in Zhujiang and Longxue Residential Communities as well as the northern part of Wanqingsha for tlie southern jiart.