摘要：過去海洋氣候學家普遍認為Labrador海為溫鹽環流深層水團主要來源，然而最近Bower et al. (2009, Nature) 以及相關觀測研究竟發現大部份Labrador海水並非沿著過去認知的全球溫鹽環流路徑流動，這馬上衝擊到全球溫鹽環流之來源、路徑與氣候之影響。本計劃將以台灣自行發展之TIMCOM海洋模式為基礎建立高解析度全球海洋模式(希冀全球解析度能提高到1/16°或1/24°)深入瞭解全球溫鹽環流、西方邊界流之變化以及對太平洋、大西洋氣候之影響，主要將著重在全球深層海洋環流系統、黑潮蜿蜒路徑以及墨西哥灣流的分離效應。本計劃會利用Lagrangian軌跡診斷以及模式與觀測的比對將用以驗證TIMCOM模式描述全球海流系統的能力；另外，藉由高解析度模式分析渦流的年平均變化和年際變動以描繪渦流的區域性特徵；最後也探討海底地形與溫鹽環流、西方邊界流及其相應變動的關鍵成因。我們希望藉由本計劃發展高解析的平行版TIMCOM，並促進學界對北大西洋與太平洋溫鹽環流及西方邊界流延伸區變動的認知，以及推估其對整體氣候變遷所可能造成的影響，最後希望藉由此模式之發展與溫鹽環流研究以增進我們對全球海洋氣候變遷之了解，期待在計畫期限內能夠追上歐美日各國在海洋溫鹽環流以及全球氣候影響之研究方向。
Abstract: Recently reported paths of constant depth floats refute the traditional conveyor belt picture of the Deep Western Boundary Current (DWBC) flow in the North Pacific. The paths of constant depth floats released into the DWBC at 700m and 1500m indicate that most of the DWBC water separates from the traditional bottom-hugging conveyor-belt path along the North American continental shelf slope before reaching the southern tip of the Grand Banks. Thus, the thermohaline circulation (THC), by which ocean currents exchange warm water in equatorial latitudes with cold water in high latitudes, has been misinterpreted and requires further investigation. It is very difficult to build a complete picture of the general circulation due to the lack of deep water data. Furthermore, recent idealized model sensitivity studies show that the turbulent abyssal flow has much bigger effect on the climatologically important Gulf Stream (GS) than the DWBC does. We propose a comprehensive study of the poorly understood abyssal flow in the northwestern Atlantic and Pacific, and its effect on the Gulf Stream and Kuroshio through highly resolved simulations. Thin, narrow, bottom-hugging density currents are a big challenge to computer models. This challenge has recently been met in simulating the depth penetration, path and transport of the salty, dense Mediterranean Overflow Water (MOW) that spills over the tiny Strait of Gibraltar sill and feeds an especially model-challenging density current. Based on these recent advances, we will further develop the high resolution Taiwan Multi-scale Community Ocean Model (TIMCOM) to investigate the DWBC and THC in both North Atlantic and Pacific.
western boundary currents
Gulf Stream separation