Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8
Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8
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DOI：
10.1029/2020gl087637
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发表时间：
2020-05
影响因子：
5.2
通讯作者：
T. Tsukada;T. Horinouchi
中科院分区：
文献类型：
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作者：
T. Tsukada;T. Horinouchi
对热带气旋风的观测仍然有限。我们提出了一种计算热带气旋切向风的新方法，该方法利用Himawari - 8等最新一代地球同步气象卫星对高频云图进行频谱分析。该方法应用于台风“兰”（2017）眼8.5小时内边界层云的可见图像。中心三分之二半径的低空切向风接近刚体旋转，并随时间增加。在它的外部是一个区域，条纹云以更高的角速度旋转，这可能是超梯度。将不对称运动可视化为内部旋转的偏离，并量化了一些中涡旋的涡度。这些不对称运动被认为是传递角动量以加速内部旋转。
Observations of the winds in tropical cyclones are still limited. We propose a new method for deriving the tangential winds in tropical cyclones, which employs a spectral analysis of high‐frequency cloud imaging by latest‐generation geostationary meteorological satellites such as Himawari‐8. The method was applied to the visible images of boundary layer clouds in the eye of Typhoon Lan (2017) over an 8.5‐hr period. The low‐level tangential winds over the central two thirds of the eye in radius were close to a rigid body rotation and increased with time. On its outside was a region with striating clouds rotating at much higher angular velocities, which may have been supergradient. Asymmetric motions were visualized as the deviation from the inner rotation, and the vorticity of some mesovortices were quantified. These asymmetric motions are suggested to transport angular momentum to accelerate the inner rotation.