2020年第7号台风“海高斯”强度和路径异常成因

On the Causation of Abnormal Intensity and Path of Typhoon Higos,the Seventh Storm in 2020

利用常规气象观测资料、NCEP全球再分析资料(1°×1°)、中国气象局台风经纬度数据和卫星云图、雷达图等资料,分析了2020年第7号台风“海高斯”活动期间西风槽、西太平洋副热带高压、环境场和垂直风切变等系统和要素变化特征,初步研究了“海高斯”近海增强以及路径北翘的成因。结果表明:西风槽东移导致副热带高压东退,是“海高斯”路径发生北翘的主要成因;异常偏高的海温和弱垂直风切变是“海高斯”近海增强的关键;低层有利的水汽辐合和高空辐散有利于TC发展。

Using conventional meteorological observations,1°×1°global reanalysis from NCEP and typhoon longitudes and latitudes data as well as the data of weather satellites and radar charts from the China Meteorological Administration,this work analyzes the variation characteristics of a westerly trough,a subtropical high over the western North Pacific,the environmental field,vertical wind shear and the meteorological elements for the active period of Typhoon Higos,the seventh storm in 2020,and runs a preliminary study on the causation for the typhoon to strengthen over offshore waters and follow a northward-turning path in the north of the South China Sea.The result is shown as follows.The fact that the westerly trough moved to the east to result in the eastward retreat of the subtropical high is mainly responsible for the northward turning of the path of Higos.Anomalously high sea surface temperature and weak vertical wind shear are the key to offshore strengthening of the typhoon.Low-level convergence and upper-level divergence of water vapor is favorable for the typhoon to grow.