超强台风“莫兰蒂”(1614)边界层结构的风廓线雷达观测分析

Analysis of Boundary Layer Structure of Super Typhoon Meranti (1614) Using Wind Profiler Radar Data

关键词:  风廓线雷达  最大切向风速高度  入流层高度  边界层结构

Key words:  wind profiler radar  height of maximum tangential wind speed  height of inflow layer  boundary layer structure

摘要:

利用翔安风廓线雷达和厦门探空雷达资料，对2016年超强台风“莫兰蒂”外雨带(距离台风中心120~220 km)和外围晴空(距离台风中心 400~630 km)边界层结构进行观测分析，结果表明：在超强台风“莫兰蒂”外雨带，风廓线雷达反演的最大切向风速高度分布在入流层下方 0.5~1.0 km 处，并且随着台风中心的靠近，最大切向风速和入流层高度都有降低的趋势，受降雨粒子的影响，风廓线雷达只能定性反映台风外雨带最大切向风速高度和入流层高度分布特征。在超强台风“莫兰蒂”外围晴空天气下，最大切向风速高度与入流层高度具有一致性，其边界层高度变化比较平稳，高度分布在 1.2~1.6 km 之间，能够定量反映台风外围晴空边界层高度分布；相对于传统热力驱动的湍流，台风系统边界层湍流主要由风切变驱动，台风外围湍流活动的增强主要发生在最大切向风速高度附近，除了风切变还有其他比较重要的驱动源，表明在台风边界层顶部附近有更加复杂的湍流活动，需要更加精细的湍流通量试验确定其来源。

Abstract:

This study employed wind profiler radar data from Xiang’an and radiosonde data from Xiamen to analyze the boundary layer structure in two distinct regions surrounding Super Typhoon Meranti in 2016: the outer rainband (120—220 km from the typhoon center) and the clear sky area (400—630 km from the typhoon center). The results showed that, in the outer rainband, the maximum tangential wind speed retrieved by the wind profiler radar was predominantly found 0.5—1.0 km below the inflow layer. As the typhoon center approached, the height of the maximum tangential wind speed and the height of the inflow layer exhibited a downward trend. The presence of rainfall particles, however, limited the wind profiler radar’s capability to provide only qualitative assessment of the distribution patterns of the height of the maximum tangential wind speed and the height of the inflow layer in the outer rainband of the typhoon. In the clear sky area, the height of the maximum tangential wind speed was consistent with the height of the inflow layer, and the height of the boundary layer remained relatively stable, ranging between 1.2—1.6 km. This allowed for a quantitative representation of the boundary layer height distribution in the clear sky area around the typhoon. Compared with thermal turbulence, the turbulence in the boundary layer of the typhoon system was mainly driven by wind shear. The enhancement of the turbulence activities around the typhoon mainly occurred near the height of the maximum tangential wind speed. In addition to wind shear, there were other important driving forces, indicating more complex turbulence activities near the top of the typhoon boundary layer. More detailed turbulence flux experiments are needed to determine the driving forces of these activities.