The Sensitivity of Southern Ocean Air‐Sea Carbon Fluxes to Background Turbulent Diapycnal Mixing Variability
The Sensitivity of Southern Ocean Air‐Sea Carbon Fluxes to Background Turbulent Diapycnal Mixing Variability
复制标题
南大洋空气-海洋碳通量对背景湍流双相混合变异的敏感性
DOI：
10.1029/2023jc019756
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Mazloff, Matthew
中科院分区：
文献类型：
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作者：
Ellison, Elizabeth;Mashayek, Ali;Mazloff, Matthew
南大洋（SO）连接着主要的海洋盆地，由于深层营养和富碳沃茨的重新出现，它承载着巨大的海气碳通量。虽然SO混合层中的风引起的湍流混合对海气通量很重要，但下面数量级较弱的背景混合的重要性还不太清楚。改变背景混合对示踪剂的直接影响，而不是由于大规模海洋环流的长期变化而产生的响应，也研究得很少。地形引起的向上传播的背风波、在混合层底部产生的风引起的向下传播的波、向南传播的内潮变浅以及海冰下的湍流都是已知的引起上层海洋背景湍流的过程，但通常不在模型中表示。在这里，我们表明，在气候模型中通常使用的一系列值（m2 s −1-m2 s −1）范围内突然改变SO中的背景混合，可能导致扰动第一年的SO年度海气CO2通量变化约70%，在实验的6年期间，SO年度海气CO2通量变化约40%，在季节时间尺度上变化更大。这主要是通过改变地表水的温度和溶解的无机碳和碱度分布。由于引起小尺度背景混合的过程具有很高的时空变异性，这项工作证明了它们在气候模式中的代表性对于精确模拟全球地球化学循环的重要性。
The Southern Ocean (SO) connects major ocean basins and hosts large air‐sea carbon fluxes due to the resurfacing of deep nutrient and carbon‐rich waters. While wind‐induced turbulent mixing in the SO mixed layer is significant for air‐sea fluxes, the importance of the orders‐of‐magnitude weaker background mixing below is less well understood. The direct impact of altering background mixing on tracers, as opposed to the response due to a longer‐term change in large‐scale ocean circulation, is also poorly studied. Topographically induced upward propagating lee waves, wind‐induced downward propagating waves generated at the base of the mixed layer, shoaling of southward propagating internal tides, and turbulence under sea ice are among the processes known to induce upper ocean background turbulence but typically are not represented in models. Here, we show that abruptly altering the background mixing in the SO over a range of values typically used in climate models ( m2s−1– m2s−1) can lead to a ∼70% change in annual SO air‐sea CO2fluxes in the first year of perturbations, and around a ∼40% change in annual SO air‐sea CO2fluxes over the 6‐year duration of the experiment, with even greater changes on a seasonal timescale. This is primarily through altering the temperature and the dissolved inorganic carbon and alkalinity distribution in the surface water. Given the high spatiotemporal variability of processes that induce small‐scale background mixing, this work demonstrates the importance of their representation in climate models for accurate simulation of global biogeochemical cycles.