Unique ocean circulation pathways reshape the Indian Ocean oxygen minimum zone with warming
Unique ocean circulation pathways reshape the Indian Ocean oxygen minimum zone with warming
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DOI：
10.5194/bg-20-4711-2023
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发表时间：
2023-11
期刊：
影响因子：
4.9
通讯作者：
Sam J. Ditkovsky;L. Resplandy;Julius J. M. Busecke
中科院分区：
文献类型：
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作者：
Sam J. Ditkovsky;L. Resplandy;Julius J. M. Busecke
抽象。全球海洋正在随着变暖而失去氧气。然而，观测和地球系统模型预测表明，这种全球海洋脱氧并不等同于热带氧气最低区（OMZ）的简单和系统性扩张。以前的研究集中在太平洋，他们表明，外OMZ脱氧和扩展的平流输送氧气供应减弱，OMZ核心充氧和合同，由于在源沃茨供应缓慢混合的组合物的转变，并在这两个制度之间的氧气重新分配OMZ体积的影响不大。在这里，我们研究的OMZ在印度洋变暖的反应，使用一个合奏的地球系统模型高排放情景实验耦合模型相互比较项目第6阶段。我们发现了类似的扩张-再分配-收缩响应，但表明印度洋独特的海洋环流路径导致比太平洋更突出的OMZ收缩和再分配制度。因此，只有最外层的体积（氧气>180 µmol kg−1）膨胀。印度洋西南部经历了广泛的氧化作用，这是由于印度尼西亚洋流提供的沃茨减少，而有利于南印度洋环流提供的高氧沃茨。由于边缘海流出（红海和波斯湾）的快速变暖和变浅以及随着变暖局部分层的增加，模型还预测了北方阿拉伯海强烈的局部脱氧。我们扩展了现有的概念框架，用于解释太平洋OMZ的反应，以解释在印度洋的反应。
Abstract. The global ocean is losing oxygen with warming. Observations and Earth system model projections, however, suggest that this global ocean deoxygenation does not equate to a simple and systematic expansion of tropical oxygen minimum zones (OMZs). Previous studies have focused on the Pacific Ocean; they showed that the outer OMZ deoxygenates and expands as oxygen supply by advective transport weakens, the OMZ core oxygenates and contracts due to a shift in the composition of the source waters supplied by slow mixing, and in between these two regimes oxygen is redistributed with little effect on OMZ volume. Here, we examine the OMZ response to warming in the Indian Ocean using an ensemble of Earth system model high-emissions scenario experiments from the Coupled Model Intercomparison Project Phase 6. We find a similar expansion–redistribution–contraction response but show that the unique ocean circulation pathways of the Indian Ocean lead to far more prominent OMZ contraction and redistribution regimes than in the Pacific Ocean. As a result, only the outermost volumes (oxygen>180 µmol kg−1) expand. The Indian Ocean experiences a broad oxygenation in the southwest driven by a reduction in waters supplied by the Indonesian Throughflow in favor of high-oxygen waters supplied from the southern Indian Ocean gyre. Models also project a strong localized deoxygenation in the northern Arabian Sea due to the rapid warming and shoaling of marginal sea outflows (Red Sea and Persian Gulf) and increases in local stratification with warming. We extend the existing conceptual framework used to explain the Pacific OMZ response to interpret the response in the Indian Ocean.