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首页> 外文期刊>Journal of Climate >The Role of Northern Sea Ice Cover for the Weakening of the Thermohaline Circulation under Global Warming
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The Role of Northern Sea Ice Cover for the Weakening of the Thermohaline Circulation under Global Warming

机译：全球变暖下北海冰盖对温盐环流减弱的作用

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An increase in atmospheric CO2 concentration and the resulting global warming are typically associated with a weakening of the thermohaline circulation (THC) in model scenarios. For the models participating in the Coupled Model Intercomparison Project (CMIP), this weakening shows a significant (r = 0.62) dependence on the initial THC strength; it is stronger for initially strong overturning. The authors propose a physical mechanism for this phenomenon based on an analysis of additional simulations with the coupled climate models CLIMBER-2 and CLIMBER-3 alpha . The mechanism is based on the fact that sea ice cover greatly reduces heat loss from the ocean. The extent of sea ice is strongly influenced by the near-surface atmospheric temperature (SAT) in the North Atlantic but also by the strength of the THC itself, which transports heat to the convection sites. Consequently, sea ice tends to extend farther south for weaker THC. Initially larger sea ice cover responds more strongly to atmospheric warming; thus, sea ice retreats more strongly for an initially weaker THC. This sea ice retreat tends to strengthen (i.e., stabilize) the THC because the sea ice retreat allows more oceanic heat loss. This stabilizing effect is stronger for runs with weak initial THC and extensive sea ice cover. Therefore, an initially weak THC weakens less under global warming. In contrast to preindustrial climate, sea ice melting presently plays the role of an external forcing with respect to THC stability.
机译：在模型场景中，大气中二氧化碳浓度的增加以及由此导致的全球变暖通常与热盐循环（THC）的减弱有关。对于参与耦合模型比较项目（CMIP）的模型，这种减弱表明其对初始THC强度有显着（r = 0.62）依赖性。对于最初的强烈倾覆，它会更强。作者基于耦合气候模型CLIMBER-2和CLIMBER-3 alpha的附加模拟分析，提出了解决此现象的物理机制。该机制是基于这样的事实，即海冰覆盖大大减少了海洋的热损失。北大西洋的近地面大气温度（SAT）强烈影响着海冰的范围，而THC本身的强度则极大地影响了海冰的强度，后者将热量传递到对流点。因此，海冰趋向于向南延伸，以降低THC。最初，较大的海冰覆盖层对大气变暖的响应更加强烈;因此，最初的THC较弱时，海冰会更加强烈地后退。这种海冰撤退趋向于加强（即稳定）THC，因为海冰撤退允许更多的海洋热损失。对于初始THC较弱且海冰覆盖范围较大的运行，这种稳定作用会更强。因此，在全球变暖的情况下，最初较弱的THC减弱程度较小。与工业化前的气候相反，海冰融化目前在THC稳定性方面起着外部强迫的作用。

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