Eddy-Induced Mesoscale and Submesoscale Variability in the North Pacific Subtropical Gyre(I)

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Project title

Code/計畫編號

MOST109-2611-M019-013

Translated Name/計畫中文名

北太平洋副熱帶環流之渦旋造成的中尺度與次中尺度的環境變化(1/4)

Project Coordinator/計畫主持人

Chun Hoe Chow

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Marine Environmental Informatics

Website

https://www.grb.gov.tw/search/planDetail?id=13540544

Year

2020

Start date/計畫起

01-08-2020

Expected Completion/計畫迄

31-07-2021

Bugetid/研究經費

1373千元

ResearchField/研究領域

海洋物理學

自2016年11月在科技部的資助下，我們於台灣與夏威夷之間的亞熱帶海域，發現三個大尺度的海洋浮游植物綻放現象與海洋中尺度渦旋(以下稱“渦旋”)的關聯，證實了這些渦旋在這“海洋沙漠區＂所扮演的重要角色。根據現場觀測與衛星觀測的資料分析，以及綜合過去文獻的科學成果，我們得知，造成每一次海洋浮游植物綻放現象的渦旋機制都不相同。換言之，渦旋能以不同的物理過程，在渦中心與邊緣增加海洋有光層中的營養鹽。在氣旋渦中心的湧升流可將高營養鹽的深海水帶到較淺的海洋有光層，而反氣旋渦則能透過加深混合層(或反氣旋渦和表面風的交互作用產生湧升流)，能增加渦旋中心海表的營養鹽。除外，渦旋的平流效應或者渦旋之間的交互作用所產生的次中尺度湧升流，可造成渦旋邊緣的海表營養鹽增加。基於這些產生海表高營養鹽的不同機制，本計畫將解決以下的科學問題: 哪個渦旋機制，在什麼時段或什麼海洋條件下，主要造成台灣東邊亞熱帶海域的海洋浮游植物綻放現象？為了提高研究效率，本計畫也將發展電腦語言程式碼，以便自動化偵測產生海表高營養鹽的不同渦旋機制。除外，為了觀測渦旋所造成的中尺度與次中尺度的流場變化，本計畫規劃了一個重複性的海上觀測，在同一個航線上進行不同時段的ADCP海流掃測。在人員訓練方面，本計畫將會有數位大學生參於資料的分析和自動化偵測渦旋機制的程式發展。Supported by the projects of the Ministry of Science and Technology (MOST) since 2016 November, three large-scale summer phytoplankton blooms were found to be associated with mesoscale eddies in the oligotrophic North Pacific subtropical gyre (NPSG) within Taiwan and Hawaii Islands. Eddy mechanisms driving these summer blooms were different, according to the in-situ and satellite observations and referring to some previous studies. In the literature to date, both cyclonic and anticyclonic eddies could increase nutrients at eddy cores and eddy peripheries via different physical processes. At the eddy cores, the cyclonic eddies could supply the nutrients to the sunlit layer via vertical eddy pumping, while the anticyclonic eddies could increase the near-surface nutrients via mixed layer deepening and/or eddy-wind induced Ekman pumping. Besides, horizontal advection and submesoscale vertical pumping induced by the mesoscale eddies could also increase the near-surface nutrients at eddy peripheries. Based on these several mesoscale-to-submesoscale physical processes, it was natural to ask which eddy mechanism was dominant to the bloom occurrence, under what oceanic conditions, during different periods. Thus, the main goals of this proposal were set to: (1) understand the different eddy mechanisms triggering the blooms in the NPSG and (2) develop a computer-language program for automatically detect different eddy roles in increasing the near-surface chlorophyll-a concentration. In addition, a repeat sea-going experiment was proposed here to observe the eddy-induced mesoscale and submesoscale variability by mainly using ship-board ADCP. Several undergraduate students were planned to be trained for data analyzing and computer-language programming.

Keyword(s)

中尺度渦旋
中尺度與次中尺度海洋變化
渦旋作用的偵測
北太平洋亞熱帶海域
Mesoscale eddies
mesoscale and submesoscale variability
eddy-role detection
subtropical North Pacific

DSpace CRIS

Eddy-Induced Mesoscale and Submesoscale Variability in the North Pacific Subtropical Gyre(I)

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