Antarctic Sea Ice Control on the Depth of North Atlantic Deep Water
Antarctic Sea Ice Control on the Depth of North Atlantic Deep Water
复制标题
南极海冰对北大西洋深水深度的控制
作者：
L. Nadeau;R. Ferrari;M. Jansen
有人认为，深海环流和分层的变化通过影响大气二氧化碳浓度，导致冰川气候和间冰期气候之间的气候变化。最近有人提出，这种变化通过两种可能的机制与南极海冰的变化有关：南极海冰纬度范围的增加和南极海冰形成速度的增加。这两种机制都会导致大西洋经向翻转环流（AMOC）向上移动到双密混合强烈的深度（2000米以上）之上，从而使AMOC与深海翻转环流脱钩。在这里，这两个假设通过一系列理想化的两盆地海洋模拟进行了检验。为了独立研究纬度冰范围增加与冰形成速率增加的影响，海冰被参数化为浮力通量为负的纬度带。结果表明，这两种机制都可以有效地解耦经向翻转循环（MOC）的两个细胞，并且它们的效果是相加的。为了说明南极海冰在 AMOC 和深海翻转单元解耦中的作用，我们对深水团的年龄进行了估计。如果海冰很厚并充当盖子，抑制海气通量，那么海冰范围及其形成速度的增加会导致深水团的急剧“老化”。通过比较不同垂直扩散率曲线的结果，突出了垂直混合的关键作用。讨论了水团年龄增加对深海碳储存的影响。
Changes in deep-ocean circulation and stratification have been argued to contribute to climatic shifts between glacial and interglacial climates by affecting the atmospheric carbon dioxide concentrations. It has been recently proposed that such changes are associated with variations in Antarctic sea ice through two possible mechanisms: an increased latitudinal extent of Antarctic sea ice and an increased rate of Antarctic sea ice formation. Both mechanisms lead to an upward shift of the Atlantic meridional overturning circulation (AMOC) above depths where diapycnal mixing is strong (above 2000 m), thus decoupling the AMOC from the abyssal overturning circulation. Here, these two hypotheses are tested using a series of idealized two-basin ocean simulations. To investigate independently the effect of an increased latitudinal ice extent from the effect of an increased ice formation rate, sea ice is parameterized as a latitude strip over which the buoyancy flux is negative. The results suggest that both mechanisms can effectively decouple the two cells of the meridional overturning circulation (MOC), and that their effects are additive. To illustrate the role of Antarctic sea ice in decoupling the AMOC and the abyssal overturning cell, the age of deep-water masses is estimated. An increase in both the sea ice extent and its formation rate yields a dramatic “aging” of deep-water masses if the sea ice is thick and acts as a lid, suppressing air–sea fluxes. The key role of vertical mixing is highlighted by comparing results using different profiles of vertical diffusivity. The implications of an increase in water mass ages for storing carbon in the deep ocean are discussed.
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具有两个封闭盆地和一个折返水道的海洋翻转环流模型
影响因子：
3.5
作者：
Ferrari R
通讯作者：
Ferrari R
影响因子：
56.9
作者：
J. Lynch‐Stieglitz;J. Adkins;W. Curry;T. Dokken;I. Hall;J. Herguera;J. Hirschi;E. Ivanova;
通讯作者：
J. Lynch‐Stieglitz;J. Adkins;W. Curry;T. Dokken;I. Hall;J. Herguera;J. Hirschi;E. Ivanova;
影响因子：
4
作者：
Gersonde, R;Crosta, X;Armand, L
通讯作者：
Armand, L
影响因子：
--
作者：
Burke, Andrea;Stewart, Andrew L.;Thompson, Andrew F.
通讯作者：
Thompson, Andrew F.
影响因子：
--
作者：
de Boer, A. M.;Sigman, D. M.;Russell, J. L.
通讯作者：
Russell, J. L.