摘要
本文采用地基雷达轨迹显示技术(Ground Based Velocity Track Display,简称GBVTD)反演的雷达风场资料,分析台风卡努(0515)在登陆期间近中心环流结构特征。轴对称环流结构分析表明,登陆前卡努轴对称切向风速最大值出现在眼墙区域2 km高度附近,最大风速半径随高度向外倾斜。轴对称径向入流主要位于低层,而上升气流主要出现在眼墙区和外围雨带区内。台风最大风速半径在登陆前几乎不变,但登陆后逐渐內缩。登陆过程中,轴对称切向风速值总体随时间呈明显减弱的趋势,但在中低层存在波动,特别是在登陆前半小时,切向风速突然增强。此外,登陆后最大轴对称切向风速高度明显抬升,伴随着外围雨带区上升流显著减弱。同时台风低层入流增强、厚度增加、范围向内和向外扩展。非对称环流结构显示:登陆过程中,台风眼墙区切向风环流和雷达回波均呈显著的一波不对称结构。其中大风速区和强降水区的位置相对于台风移动方向和垂直风切变方向有显著的规律性分布。由于卡努移动速度较快,且登陆期间受强垂直风切变影响。因此,其不对称结构应是垂直风切、台风移动和陆气相互作用三者共同作用的结果。
Landfalling typhoon Khanun（0515） was observed by the CINRAD WSR-98D radar on the southeast coast of China.This study documents the structure and evolution of typhoon Khanun＇s circulation during its landing by using circulation derived from the Ground Based Velocity Track Display（GBVTD） technique.The axisymmetric structure analysis results are revealed as follows： Before landfall,the maximum tangential wind existed in the eyewall at about 2-km height and the radius of the maximum wind（RMW） tilted outward at about 30 degrees from the zenith.Meanwhile the inflow was confined at the low level and strong updrafts existed in both eyewall and outer rain band.During the landfall stage,the axisymmetric tangential wind decreased obviously,accompanied with slight contraction of the RMW and few fluctuation of wind speed at the low level.After landfall,the low-level inflow intensified and expanded both inward and outward in the radial direction,while the maximum tangential wind was elevated to 3-km height.Meanwhile,the updraft in outer rain band weakened obviously.The asymmetric circulation structure analysis results exhibited the distinct wave-1 structure during landfall.Both the maximum tangential wind and the maximum rainfall have remarkable regular locations in relation to the shear vector and the storm motion.Since Khanun was fast-moving typhoon and was in an environment of strong vertical wind shear,its asymmetry structure could be attributed to the influences of vertical wind shear,storm motion,and land-typhoon interaction.
出处
《大气科学》
CSCD
北大核心
2011年第1期68-80,共13页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展计划项目2009CB421502
国家自然科学基金资助项目40975011、40505004
中国气象局公益性行业(气象)科研专项(GYHY200906004)
关键词
登陆台风
地基雷达轨迹显示技术
轴对称环流结构
非对称结构
landfalling typhoon
Ground Based Velocity Track Display（GBVTD） technique
axisymmetric circulation structure
asymmetric structure
