台风“圆规”造成西沙强降水的成因分析

Analysis of the Causes of Heavy Rainfall in Xisha Caused by Typhoon“Compass”

为掌握台风产生的直接和间接暴雨对农业的影响,利用MICAPS数据、西沙自动站及双偏振雷达资料、风云四号气象卫星数据,分析2118号台风“圆规”影响过程。结果表明:台风“圆规”受强盛的西太平洋副热带高压南侧偏东气流的引导,路径稳定向西行进影响西沙,“圆规”云系呈现不对称结构,强盛的赤道西风,不断有水汽和能量的输入南部和东侧,使得这两侧的对流云系发展旺盛。通过卫星云图和西沙双偏振雷达进一步分析“圆规”强降水中尺度特征可知,台风南部的强螺旋云系和台风强度的增强是西沙降水范围广、雨势较强的原因,台风“圆规”降雨效率高,以大粒子雨滴为主。

In order to understand the impact of direct and indirect rainstorm caused by typhoon on agriculture,MICAPS data,Xisha automatic station and dual polarization radar data,and FY-4 meteorological satellite data were used to analyze the impact process of typhoon 2118“Compass”.The results show that Typhoon“Compass”is guided by the strong easterly airflow on the south side of the Western Pacific subtropical high,and its path steadily moves westward,affecting Xisha.The“Compass”cloud system presents an asymmetric structure,with strong equatorial westerly winds and continuous input of water vapor and energy to the south and east,making the convective cloud systems on both sides develop vigorously.Further analysis of the mesoscale characteristics of the“Compass”heavy rainfall through satellite cloud images and Xisha dual polarization radar indicates that the strong spiral cloud system in the southern part of the typhoon and the enhancement of typhoon intensity are the reasons for the wide range and strong rainfall in Xisha.The“Compass”typhoon has high rainfall efficiency,mainly consisting of large particle raindrops.