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Hokkaido University Collection of Scholarly and Academic Papers >
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Stationary and Transient Asymmetric Features in Tropical Cyclone Eye with Wavenumber-1 Instability : Case Study for Typhoon Haishen (2020) with Atmospheric Motion Vectors from 30-Second Imaging
| Title: | Stationary and Transient Asymmetric Features in Tropical Cyclone Eye with Wavenumber-1 Instability : Case Study for Typhoon Haishen (2020) with Atmospheric Motion Vectors from 30-Second Imaging |
| Authors: | Horinouchi, Takeshi Browse this author →KAKEN DB | | Tsujino, Satoki Browse this author →KAKEN DB | | Hayashi, Masahiro Browse this author | | Shimada, Udai Browse this author →KAKEN DB | | Yanase, Wataru Browse this author →KAKEN DB | | Wada, Akiyoshi Browse this author →KAKEN DB | | Yamada, Hiroyuki Browse this author |
| Keywords: | Atmosphere | | Instability | | Tropical cyclones | | Satellite observations |
| Issue Date: | Jan-2023 |
| Publisher: | American Meteorological Society |
| Journal Title: | Monthly Weather Review |
| Volume: | 151 |
| Issue: | 1 |
| Start Page: | 253 |
| End Page: | 273 |
| Publisher DOI: | 10.1175/MWR-D-22-0179.1 |
| Abstract: | Dynamics of low-level flows in the eye of Typhoon Haishen (2020) in its late phase of intensification are investigated with a special rapid-scan observation of the Himawari-8 geosynchronous satellite conducted every 30 s. This is accomplished by deriving storm-relative atmospheric motion vectors at an unprecedentedly high spatiotemporal resolution by tracking clouds across five consecutive visible-light reflectivity. The overall low-level circulation center was situated several kilometers away from the storm center defined in terms of the inner edge of the lower part of eyewall clouds. The shift direction is rearward of the storm translation, consistently with a numerical study of the tropical cyclone (TC) boundary layer. Over the analysis period of 10 h, azimuthal-mean tangential wind around this center was increased at each radius within the eye, and the rotational angular velocity was nearly homogenized. The instantaneous low-level circulation center is found to orbit around the overall circulation center at distances around 5 km. Its orbital angular speed was close to the maximum angular speed of azimuthal-mean tangential winds. This rotating transient disturbance is found to transport angular momentum inward, which explains the tangential wind increase and the angular velocity homogenization in the eye. These features are consistent with an algebraically growing wavenumber-1 barotropic instability, whose impact on TC structures has not been explored. This instability enhances wavenumber-1 asymmetry in ring-shaped vorticity, which can be induced by various processes such as translation, environmental shear, and exponential barotropic instability. Therefore, it may appear broadly in TCs to affect wind distribution in their eyes. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/88545 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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