Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO2
Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO2
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DOI：
10.1007/s00382-012-1650-3
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发表时间：
2013-10-01
期刊：
影响因子：
4.6
通讯作者：
Williams, Richard G.
中科院分区：
文献类型：
--
作者：
Lauderdale, Jonathan M.;Garabato, Alberto C. Naveira;Williams, Richard G.
本文利用一套粗分辨率、全球耦合的海洋环流和生物地球化学实验，研究了理想的南大洋风驱动环流变化对大气CO2和海洋碳储量的影响，这些实验具有参数化的涡旋活动和表面浮力强迫的适度变化，每个实验综合了5000年。南大洋经向翻转或剩余环流与大气CO2呈正相关，南半球偏强或向北移动的西风导致剩余环流增加，富碳深水上涌和海洋脱气增加，使大气pCO(2)增加约20 μ matm；较弱或向南移动的风导致相反的结果。在我们的模型中，海洋碳储量通过饱和、不平衡和生物成因（软组织和碳酸盐）储层的对比变化而变化，每个储层变化为0 (10-100)PgC，所有这些都导致大气CO2的净异常。残余倾覆的增加加深了全球斜斜，使上层海洋变暖，减少了饱和碳库。富含碳和营养的深水上升流的增加和低效的生物活性导致未利用的营养物质俯冲到海洋内部，减少了为北半球提供通气的中间和模式水的生物成因碳库，并且由于在表面停留时间的减少，使模式水中的不平衡碳库更具正电性。风引起的模式碳储量变化主要是全球斜斜的响应，尽管当西风峰值改变其纬度，改变其与德雷克通道的接近程度并改变向南翻转回流的深度范围时，存在额外的深海响应。西风向北移动隔绝了密集的等平线，使生物碳积聚在南半球的深海中，而向南移动则使密集的等平线变得浅滩，在南大洋露头，减少了深海中的生物碳储存。
The effect of idealized wind-driven circulation changes in the Southern Ocean on atmospheric CO2 and the ocean carbon inventory is investigated using a suite of coarse-resolution, global coupled ocean circulation and biogeochemistry experiments with parameterized eddy activity and only modest changes in surface buoyancy forcing, each experiment integrated for 5,000 years. A positive correlation is obtained between the meridional overturning or residual circulation in the Southern Ocean and atmospheric CO2: stronger or northward-shifted westerly winds in the Southern Hemisphere result in increased residual circulation, greater upwelling of carbon-rich deep waters and oceanic outgassing, which increases atmospheric pCO(2) by similar to 20 mu atm; weaker or southward-shifted winds lead to the opposing result. The ocean carbon inventory in our model varies through contrasting changes in the saturated, disequilibrium and biogenic (soft-tissue and carbonate) reservoirs, each varying by O(10-100) PgC, all of which contribute to the net anomaly in atmospheric CO2. Increased residual overturning deepens the global pycnocline, warming the upper ocean and decreasing the saturated carbon reservoir. Increased upwelling of carbon- and nutrient-rich deep waters and inefficient biological activity results in subduction of unutilized nutrients into the ocean interior, decreasing the biogenic carbon reservoir of intermediate and mode waters ventilating the Northern Hemisphere, and making the disequilibrium carbon reservoir more positive in the mode waters due to the reduced residence time at the surface. Wind-induced changes in the model carbon inventory are dominated by the response of the global pycnocline, although there is an additional abyssal response when the peak westerly winds change their latitude, altering their proximity to Drake Passage and changing the depth extent of the southward return flow of the overturning: a northward shift of the westerly winds isolates dense isopycnals, allowing biogenic carbon to accumulate in the deep ocean of the Southern Hemisphere, while a southward shift shoals dense isopycnals that outcrop in the Southern Ocean and reduces the biogenic carbon store in the deep ocean.