Overturning Circulation in an Eddy-Resolving Model : The Effect of the Pole-to-Pole Temperature Gradient
Overturning Circulation in an Eddy-Resolving Model : The Effect of the Pole-to-Pole Temperature Gradient
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涡旋分辨模型中的翻转环流：极间温度梯度的影响
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
P. Cessi
中科院分区：
文献类型：
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作者：
C. Wolfe;P. Cessi
在一个配置在大致代表大西洋扇区的理想域中的涡旋分辨海洋模式中，研究了极-极表面温差对深层层结和全球纬向翻转环流（MOC）强度的影响。与层流相比，中尺度涡旋导致平均分层和MOC的质的差异（即，无涡流）模型。例如，在南极绕极流（ACC）的模型表示中，流体的扩散不再依赖于ACC中存在的底槛。此外，深水和底层水质量-大致代表北大西洋深水（NADW）和南极底层水（ABW），分别-被涡侵蚀，使其纬向和纬向范围远小于层流情况。结果表明，当北极温度足够高时，北方深层水的形成受到抑制，中深层环流小而弱，而深层环流大而强。相反，当北极温度在南槽温度范围内时，中层环流大而强，深层环流振幅减小，这与MOC层流理论的预测一致。与层流理论相反，即使北方下沉点的温度比海峡中的任何温度都高，也会形成实际上很强的深层层结。实际上，后一种情况下的中深度分层实际上比前一种情况下更强。
The effect of the pole-to-pole surface temperature difference on the deep stratification and the strength of the global meridional overturning circulation (MOC) is examined in an eddy-resolving ocean model configured in an idealized domain roughly representing the Atlantic sector. Mesoscale eddies lead to qualitative differences in the mean stratification and the MOC compared to laminar (i.e., eddy free) models. For example, the spreading of fluid across the model’s representation of the Antarctic Circumpolar Current (ACC) no longer relies on the existence of a sill in the ACC. In addition, the deep- and bottom-water masses— roughly representing North Atlantic Deep Water (NADW) and Antarctic Bottom Water (ABW), respectively—are eroded by the eddies so that their zonal and meridional extents are much smaller than in the laminar case. It is found that if the north pole temperature is sufficiently warm, the formation of northern deep water is suppressed and the middepth cell is small and weak while the deep cell is large and vigorous. In contrast, if the north pole temperatureis in the range of the southern channeltemperatures,the middepth cell is large andstrong while the deep cell has a reducedamplitude.This result is consistentwith the predictionsof the laminar theory of the MOC. In contrast to the laminar theory, realistically strong deep stratification is formed even if the temperature at the northern sinking site is warmer than any temperature found in the channel. Indeed, middepth stratification is actually stronger in the latter case than the former case.