On the Role of the Gulf Stream in the Changing Atlantic Nutrient Circulation During the 21st Century
On the Role of the Gulf Stream in the Changing Atlantic Nutrient Circulation During the 21st Century
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DOI：
10.1002/9781119428428.ch4
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发表时间：
2019-05
期刊：
影响因子：
--
通讯作者：
D. Whitt
中科院分区：
文献类型：
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作者：
D. Whitt
墨西哥湾流是大西洋经向翻转环流（AMOC）上肢的一部分，也是北大西洋副热带环流的西边界流。墨西哥湾流也是一种营养流。从佛罗里达海峡到哈特拉斯角，它以全球显著的速度沿着美国东部大陆边缘运输海洋浮游植物生长所必需的大量营养物质（硝酸盐、磷酸盐、硅酸盐）。在哈特拉斯角，墨西哥湾流与海岸分离，将其营养物质带离大陆坡向东北方向进入深水区。在那里，最近的热带、亚热带和亚极地起源的水汇聚在一起，在全球海洋环流的一个大交汇处，体积和营养输送都增加了。再往东，在纽芬兰大浅滩附近，墨西哥湾流的水和营养物再次分流到亚热带和亚极地环流中。当营养物和水向北移动时，它们沿着倾斜的等斜线上升，最终平流到地表混合层或被季节性混合层加深带走。这种向上的养分通量由与物理和生物地球化学过程有关的向下的养分通量补偿。进入混合层的大量无机营养物直接转化为密度更大的北大西洋深水，并随着进入的水向大气散失热量而下沉。然而，另一部分进入混合层的无机营养物质通过浮游植物转化为有机形式。这些有机养分的一部分通过颗粒沉降到较稠密的水中，在那里它被再矿化，而有机养分的另一部分（即不下沉的溶解部分）被转化
The Gulf Stream is part of the upper limb of the Atlantic meridional overturning circulation (AMOC) and the western boundary current of the North Atlantic sub tropical gyre. The Gulf Stream is also a nutrient stream. It transports macronutrients (nitrate, phosphate, silicate) necessary for marine phytoplankton growth along the eastern continental margin of the United States from the Straits of Florida to Cape Hatteras at globally significant rates. At Cape Hatteras, the Gulf Stream separates from the coast and carries its nutrients to the northeast off the continental slope and into deep water. There, waters of recent tropical, subtropical and subpolar origins con verge and both the volume and nutrient transport increase in a great junction of the global ocean circulation. Further east, near the Grand Banks of Newfoundland, the waters and nutrients of the Gulf Stream diverge again into the subtropical and subpolar gyres. As nutrients and water move northward, they rise along sloping isopycnals and are eventually advected into the surface mixed layer or entrained by seasonal mixed‐layer deepening. This upwards nutrient flux is compensated for by downwards nutrient fluxes associated with physical and biogeochemical processes. A significant fraction of the inorganic nutrient entering the mixed layer is trans formed directly to denser North Atlantic Deep Water and sinks as the incoming water loses heat to the atmosphere. However, another significant fraction of the inor ganic nutrient entering the mixed layer is converted to organic form by phytoplankton. A fraction of this organic nutrient sinks via particles to denser water, where it is remineralized, and the other fraction of the organic nutrient (i.e., the nonsinking dissolved part) is transformed On the Role of the Gulf Stream in the Changing Atlantic Nutrient Circulation During the 21st Century