Thermohaline circulation and interaction between ice shelf cavities and the adjacent open ocean
Thermohaline circulation and interaction between ice shelf cavities and the adjacent open ocean
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DOI：
10.1029/97jc00891
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发表时间：
1997-07-15
影响因子：
3.6
通讯作者：
Determann, J
中科院分区：
文献类型：
--
作者：
Grosfeld, K;Gerdes, R;Determann, J
冰架空腔内的环流系统是由冰的融化和冻结引起的浮力通量和空腔与开阔海洋交界面的水平压力梯度驱动的。因此，公海的流入和流出模式和水文影响了空腔内的一般水文条件，这至少提供了融化和冻结过程的可能性。将三维海洋环流模型应用于理想的冰架空腔几何形状和地形冰架屏障处的开放海洋，我们发现了控制这两个系统相互作用的重要参数。对不同的冰架和海底地形以及公海强迫机制的理想化研究表明，由于水柱厚度的突然减少，冰架边缘是正压相互作用的天然屏障。由于水柱厚度和科里奥利力决定了地转流的特征，因此在公海和冰架腔中出现了分离的环流系统。只有在水柱厚度恒定的地区，从海洋学的角度来看，在屏障上可以观察到恒定的f/H等高线，增加的正压流才能超越冰边缘并使冰架下面的水团通风。这种情况只发生在侧向倾斜的侧壁或深凹处，例如在威德尔海南部。在所有其他情况下，冰架空腔内的环流是封闭的，几乎不受屏障外水文的影响。
The circulation system in an ice shelf cavity is driven by buoyancy fluxes due to melting and freezing of ice and horizontal pressure gradients at the interface between the cavity and the open ocean. Hence the inflow and outflow pattern and the hydrography in the open ocean influence the general hydrographic condition in the cavity, which at least provides the potential for melting and freezing processes. Applying a three-dimensional ocean general circulation model to an idealized ice shelf cavity geometry coupled with an open ocean at a topographic ice shelf barrier, we found an important parameter controlling the interaction between these two systems. Idealized studies for different ice shelf and sea bottom topographies and forcing mechanisms for the open ocean show that the ice shelf edge represents a natural barrier for barotropic interaction, because of the sudden decrease in water column thickness. Since the water column thickness and the Coriolis force determine the characteristics for geostrophic flow, separated circulation systems arise for the open ocean and the ice shelf cavity. Only in areas where constant water column thickness and, from the oceanographic point of view, constant f/H contours can be observed across the barrier, an increased barotropic current can surmount the ice edge and ventilate the water mass beneath the ice shelf. This is only the case at lateral sloping sidewalls or at deep depressions, which can be found, for example, in the southern Weddell Sea. In all other cases the circulation in the ice shelf cavity is closed and almost unaffected by the hydrography outside the barrier.