台风“山竹”降水非对称特征及其与环境流场的相互作用研究

ON THE ASYMMETRIC CHARACTERISTICS OF TYPHOON “MANGKHUT” PRECIPITATION AND ITS INTERACTION WITH ENVIRONMENTAL FLOW FIELD

关键词:  热带气旋  垂直风切变  非对称降水  数值模拟  环境流场

Key words:  tropical cyclone  vertical wind shear  asymmetric precipitation  numerical simulation  environmental flow field

摘要:

基于卫星降水数据和再分析资料，识别了台风“山竹”的降水非对称特征及其与垂直风切变的相关性，并进一步使用WRF模式数值模拟探究了非对称降水引发的热带气旋内部动力过程对环境流场的反馈作用。(1) 台风“山竹”降水分布表现出明显的非对称性，强降水主要集中在南侧，而台风的平均风切变指向西南侧，强降水总是位于顺风切变的左侧。(2) 台风发展初期风切变指向强降水方位，之后逆时针旋转并不断增大，转至指向南侧时达到最大值，之后逐渐减小。(3) 非对称降水位置的改变伴随着非对称风场的改变，并影响着非对称温压场变化，而温压场的变化又进一步改变非对称风和降水，所以台风与环境流场存在着相互影响的反馈关系。

Abstract:

Based on satellite-observed precipitation data and reanalysis data, this paper identifies the asymmetric characteristics of Typhoon “Mangkhut” precipitation and its correlation with vertical wind shear, and further uses WRF for numerical simulation to explore the feedback effect of asymmetric precipitation induced internal dynamic process on environmental flow. The main conclusions are as follows: (1) The precipitation distribution of Typhoon “Mangkhut” shows obvious asymmetry. It is mainly concentrated in the south, while the average wind shear of the typhoon points to the southwest, and the precipitation is always on the left side of the downshear. (2) At the initial stage of typhoon development, the wind shear points to the direction of heavy precipitation, rotates counterclockwise and increases continuously. It reaches the maximum when turning to the south, and then decreases gradually. (3) The change of asymmetric precipitation location is accompanied by the change of asymmetric wind field, and it affects the change of asymmetric temperature and pressure field; the change of temperature and pressure field further changes the asymmetric wind and precipitation. Therefore, there is an interactive feedback between Typhoon “Mangkhut” and the environmental flow field.