Enhanced vertical mixing in the glacial ocean inferred from sedimentary carbon isotopes
Enhanced vertical mixing in the glacial ocean inferred from sedimentary carbon isotopes
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DOI：
10.1038/s43247-021-00239-y
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发表时间：
2021-04
影响因子：
7.9
通讯作者：
S. Wilmes;J. Green;A. Schmittner
中科院分区：
文献类型：
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作者：
S. Wilmes;J. Green;A. Schmittner
重建末次冰盛期海洋的环流、混合和碳含量仍然具有挑战性。最近的假设表明，大西洋浅水区的纬向翻转环流或层化的增加会减少垂直混合，隔离深海并增加碳储存，从而有助于降低大气CO2浓度。在这里，使用合奏的海洋模拟，我们评估的潮汐能耗散的变化，由于较低的海平面对海洋混合，循环和碳同位素分布的影响。我们发现，增加潮汐混合加强深海流速和降低放射性碳和δ 13 C在大西洋深处的垂直梯度。较浅的翻转环流和更有力的混合模拟适合沉积物同位素数据最好。我们的研究结果，这是保守的，提供了观测支持，垂直混合在冰川大西洋可能已经增强，由于更有力的潮汐消散，尽管变浅的翻转环流和分层的增加。
Reconstructing the circulation, mixing and carbon content of the Last Glacial Maximum ocean remains challenging. Recent hypotheses suggest that a shoaled Atlantic meridional overturning circulation or increased stratification would have reduced vertical mixing, isolated the abyssal ocean and increased carbon storage, thus contributing to lower atmospheric CO2concentrations. Here, using an ensemble of ocean simulations, we evaluate impacts of changes in tidal energy dissipation due to lower sea levels on ocean mixing, circulation, and carbon isotope distributions. We find that increased tidal mixing strengthens deep ocean flow rates and decreases vertical gradients of radiocarbon andδ13C in the deep Atlantic. Simulations with a shallower overturning circulation and more vigorous mixing fit sediment isotope data best. Our results, which are conservative, provide observational support that vertical mixing in the glacial Atlantic may have been enhanced due to more vigorous tidal dissipation, despite shoaling of the overturning circulation and increases in stratification.