Coastlines at Risk of Hypoxia From Natural Variability in the Northern Indian Ocean
Coastlines at Risk of Hypoxia From Natural Variability in the Northern Indian Ocean
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DOI：
10.1029/2021gb007192
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发表时间：
2022-06
影响因子：
5.2
通讯作者：
J. Pearson;L. Resplandy;M. Poupon
中科院分区：
文献类型：
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作者：
J. Pearson;L. Resplandy;M. Poupon
沿海缺氧有害的低含氧量是一个日益严重的问题，危及沿海生态系统和经济。北方印度洋特别容易受到人为影响，巨大的自然发生的氧气最低区，以及与季节性季风和年际印度洋偶极子（IOD）相关的强烈变化。我们评估自然因素如何影响沿海缺氧的风险相结合的氧气测量与卫星观测，以研究如何IOD放大或抑制季节性缺氧与亚洲季风。我们表明，在季节性和年际时间尺度上，缺氧是由风和沿海开尔文波驱动的缺氧沃茨上涌到大陆架和加强生物反馈（增加地下需氧量）控制的。从季节性来看，夏季/秋季阿拉伯海西部缺氧的风险最高（缺氧概率为71%）。IOD造成的主要年度影响发生在孟加拉湾东部（EBoB）沿着正阶段，沿海缺氧的风险在夏季/秋季（21%-46%）和冬季/春季（31%-42%）从中度增加到高度，以及沿着阿拉伯海东部（即，印度，巴基斯坦），在夏季/秋季，风险从高降至中等（53%-34%）。在负IOD阶段，EBoB也会受到强烈影响，此时风险从全年的中等水平降至低水平（25%至25%）。这种缺氧风险的流域尺度测绘是帮助国家和国际监测、预测和减轻缺氧对沿海生态系统和生态系统服务影响的关键。
Coastal hypoxia—harmfully low levels of oxygen—is a mounting problem that jeopardizes coastal ecosystems and economies. The northern Indian Ocean is particularly susceptible due to human‐induced impacts, vast naturally occurring oxygen minimum zones, and strong variability associated with the seasonal monsoons and interannual Indian Ocean Dipole (IOD). We assess how natural factors influence the risk of coastal hypoxia by combining a large set of oxygen measurements with satellite observations to examine how the IOD amplifies or suppresses seasonal hypoxia tied to the Asian Monsoon. We show that on both seasonal and interannual timescales hypoxia is controlled by wind‐ and coastal Kelvin wave‐driven upwelling of oxygen‐poor waters onto the continental shelf and reinforcing biological feedbacks (increased subsurface oxygen demand). Seasonally, the risk of hypoxia is highest in the western Arabian Sea in summer/fall (71% probability of hypoxia). Major year‐to‐year impacts attributed to the IOD occur during positive phases along the eastern Bay of Bengal (EBoB), where the risk of coastal hypoxia increases from moderate to high in summer/fall (21%–46%) and winter/spring (31%–42%), and along the eastern Arabian Sea (i.e., India, Pakistan) where the risk drops from high to moderate in summer/fall (53%–34%). Strong effects are also seen in the EBoB during negative IOD phases, when the risk reduces from moderate to low year‐round (∼25% to ∼5%). This basin‐scale mapping of hypoxic risk is key to aid national and international efforts that monitor, forecast, and mitigate the impacts of hypoxia on coastal ecosystems and ecosystem services.