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107/03/13 14:00 中央研究院環境變遷研究中心黃怡之博士後研究 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2018-03-06演 講 公 告
主講人：黃怡之 博士後研究
地點：中央大學科學一館S-325教室
摘要：
講題：Looping tracks associated with tropical cyclones approaching an isolated mountain. Part I: Essential parameters
主講人：黃怡之 博士後研究
中央研究院環境變遷研究中心
時間：3月13日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
Essential parameters for making a looping track when a westward-moving tropical cyclone (TC) approaches a mesoscale mountain are investigated by examining several key nondimensional control parameters with a series of systematic, idealized numerical experiments, such as U/Nh, Vmax/Nh, U/fLx, Vmax/fR, h/Lx, and R/Ly. Here U is the uniform zonal wind velocity, N the Brunt-Vaisala frequency, h the mountain height, f the Coriolis parameter, the maximum tangential velocity at a radius of from the cyclone center and Lx is the halfwidth of the mountain in the east-west direction. It is found that looping tracks (a) tend to occur under small U/Nh and U/fLx, moderate h/Lx, and large Vmax/Nh, which correspond to slow movement (leading to subgeostrophic flow associated with strong orographic blocking), moderate steepness, and strong tangential wind associated with TC vortex; (b) are often accompanied by an area of perturbation high pressure to the northeast of the mountain, which lasts for only a short period; and (c) do not require the existence of a northerly jet. The nondimensional control parameters were consolidated into a TC looping index (LI), which was tested by several historical looping and non-looping typhoons approaching Taiwan’s Central Mountain Range (CMR) from east or southeast. It was found that LI < 0.0125 may serve as a criterion for looping track to occur.
最後修改時間：2018-03-06 PM 3:45
