https://scholars.lib.ntu.edu.tw/handle/123456789/641574
標題: | An Observational Study on the Rapid Intensification of Typhoon Chanthu (2021) near the Complex Terrain of Taiwan | 作者: | Fang, Wei Ting Chang, Pao Liang MING-JEN YANG |
關鍵字: | Hurricanes/typhoons | Intensification | Radars/Radar observations | Shear structure/flows | Surface observations | Topographic effects | 公開日期: | 1-三月-2024 | 卷: | 152 | 期: | 3 | 起(迄)頁: | 769 | 來源出版物: | Monthly Weather Review | 摘要: | Intensification of Typhoon Chanthu (2021) along the eastern coast of Taiwan was accompanied by pronounced asymmetry in eyewall convection dominated by wavenumber-1 features, as observed by a dense radar network in Taiwan. The maximum wind speed at 3-km altitude, retrieved from radar observations, exhibited a rapid increase of approximately 18 m s-1 within an 11-h period during the intensification stage, followed by a significant decrease of approximately 19 m s-1 within 8 h during the weakening stage. Namely, Chanthu underwent both rapid intensification (RI) and rapid weakening (RW) within the 24-h analyzed period, posing challenges for intensity forecasts. During the intensifying stages, the region of maximum eyewall convection asymmetry underwent a sudden cyclonic rotation from the eastern to the northern semicircle immediately after the initiation of terrain-induced boundary inflow from the south of the typhoon, as observed by surface station data. This abrupt rotation of eyewall asymmetry exhibited better agreement with radar-derived vertical wind shear (VWS) than that derived from global reanalysis data. This finding suggests that the mesob-scale VWS is more representative for tropical cyclones than meso-α-scale VWS when the terrain-induced forcing predominates in the environmental conditions. Further examination of the radar-derived VWS indicated that the VWS profile pattern provided a more favorable environment for typhoon intensification. In summary, Chanthu's RI was influenced by the three factors: 1) terrain-induced boundary inflow from the south of the typhoon, observed by surface station data; 2) low-level flow pointing toward the upshear-left direction; and 3) weak upper-level VWS. |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/641574 | ISSN: | 00270644 | DOI: | 10.1175/MWR-D-23-0155.1 |
顯示於: | 大氣科學系 |
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