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Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8
Author(s) -
Tsukada Taiga,
Horinouchi Takeshi
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087637
Subject(s) - eye , typhoon , geostationary orbit , tropical cyclone , rotation (mathematics) , inner core , meteorology , maximum sustained wind , angular momentum , vorticity , radius , vortex , core (optical fiber) , geology , boundary layer , physics , satellite , wind shear , wind speed , geometry , geophysics , optics , mechanics , astronomy , classical mechanics , mathematics , computer security , computer science , wind gradient
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.