A Stduy on the Vertical Structure and Surface Characteristics of Green Island Wake Induced by Kuroshio (II)-1

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Project title

Code/計畫編號

MOST107-2611-M019-022

Translated Name/計畫中文名

子計畫：黑潮引起的綠島尾流垂直結構與表面特徵 (Ⅱ)-1

Project Coordinator/計畫主持人

Hung-Jen Lee

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

何宗儒

Department/Unit

Department of Marine Environmental Informatics

Website

https://www.grb.gov.tw/search/planDetail?id=12674483

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

31-07-2019

Co-Investigator(s)

Chung-Ru Ho

Bugetid/研究經費

1437千元

ResearchField/研究領域

海洋科學

黑潮為北太平洋的西側邊界流，為一股強、快的洋流，當黑潮流經綠島會使島嶼後方因不穩定而產生尾流，甚至形成渦街(vortex street)，這些現象可從衛星遙測影像中清楚看到。渦流在綠島後方引起垂直混合作用，形成相對較冷、高鹽度及葉綠素濃度較高的海面環境。這種不穩定波動造成的混合過程，對黑潮的影響，還不是很清楚，值得深入研究。在第一年計畫中利用衛星遙測海面溫度影像已得知綠島島嶼尾流受短時間大氣迫使的影響，也發現綠島尾流基本上有四種型態，分別是(1)僅在島嶼後方產生一冷水團、(2)強烈尾流向下游延伸，並無擺盪現象、(3)尾流擺盪發生，但氣旋與反氣旋並不對稱、(4)如馮卡曼渦街的尾流，此四種島嶼尾流出現的機率有極大的差異。因此第二年度計畫的重點將利用船測及水下滑翔機的實測資料，配合衛星遙測影像，輔以數值模擬以探討衛星觀測到不同尾流型態產生的動力機制及其相對應的垂直結構變化。研究結果將可進一步了解綠島尾流對黑潮及附近水團混合作用的影響，以提供日後黑潮發電廠址選擇的參考。Kuroshio is a western boundary current in the North Pacific. It is a strong, fast, and relative steady current. There could be an island wake even though a vortex street occurred in the lee of the island when Kuroshio passes by Green Island. Because of the vertical mixing process, waters with colder, saltier, and higher chlorophyll concentration are observed on the sea surface of the wake area. This kind of vertical mixing is still not clearly understood. From the investigation in the first year of this project, we found that the island wakes could be forced by winds. We also found that there are four types of the wake from satellite sea surface temperature images. The most occurred type is that the wake occurs alone, which takes about 86.7% of the island wake pattern. The other three types are the wake occurs with a tail stretching downstream (4.0%); the wake occurs with a small anticyclonic cold core but no tail stretching downstream (6.8%); and an S-shaped meandering wake occurs (2.5%). Therefore, the aims of this proposal are (1) to understand the mechanisms of the different-type wake observed from satellite images using satellite remotely-sensed data and a numerical model, and (2) to find out the vertical structures of the different-type wakes with ship and glider measurements and a numerical model. The results may improve a further understand of the mixing process between the wake water and the Kuroshio water and provide more information for considering the potential site of Kuroshio power plant.

Keyword(s)

尾流
黑潮
綠島
衛星遙測
數值模式模擬
水下滑翔機
wake
Kuroshio
Green Island
satellite remote sensing
numerical model simulation
glider

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A Stduy on the Vertical Structure and Surface Characteristics of Green Island Wake Induced by Kuroshio (II)-1

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