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109/10/06 14:00 臺灣大學海洋研究所許哲源助理教授 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2020-09-29演 講 公 告
主講人：許哲源 助理教授
地點：中央大學科學一館S-325教室
摘要：
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講題：Path of the Momentum from Tropical Cyclones into the Upper Ocean
主講人：許哲源 助理教授
臺灣大學海洋研究所
時間：10月06日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
Tropical cyclones as severe weather systems born in the tropical ocean, can cause devastating damages to the coastlines, such as the storm surges. For the response of the upper ocean to the tropical cyclones, the wind can force strong near-inertial current thereby the shear instability mixing. The entrainment of the cold water from the seasonal thermocline due to the turbulent mixing will decrease the sea surface temperature, and then affect the air-sea heat fluxes to the intensification of storms. The measurements taken by the EM-APEX floats under five tropical cyclones, including Frances 2004, Gustav 2008, Ike 2008, Fanapi 2010 and Megi 2010, are used to compute the drag coefficients Cd, which can be regarded as the efficiency for transferring momentum from the storms into the upper ocean. Compared to the conventional parameterization of Cd using the wind speed |U10|, we propose a new parameterization based on the effective wind duration ζ. The Cd(ζ) can largely decrease the scattering of drag coefficient results between different storms, suggesting that the spatial variation of dominant wave direction and duration for forcing the wind waves are both important to the Cd. That is, surface waves play an important role in the path of the momentum from the tropical cyclones into the upper ocean. Future field experiments for observing the surface waves under tropical cyclones are required.
最後修改時間：2020-10-06 PM 5:45
