Over the past decades a variety of ocean general circulation models have been developed, distinguishing themselves principally in their choice of discretization for the vertical dimension. The first type of ocean model to be developed was the z-level model (Bryan, 1969) in which the vertical is discretized based on constant geopotential surfaces. Next an isopycnic-coordinate model was presented (Bleck and Boudra, 1981) in which the vertical is divided into layers of constant density. The motivation for this layered approach is the belief that, below the surface mixed layer, the flow in the ocean occurs primarily along constant density surfaces and not along constant geopotentials. Subsequently, sigma-coordinate models (Blumberg and Mellor, 1987) were developed in which the vertical coordinate is bathymetry-following. The motivation being the desire not to lose vertical resolution over shallow, continental shelf regions as may occur with z-level or isopycnic-coordinate models.
Each approach to vertical discretization has strengths and weaknesses, and the sub ice shelf cavity with its characteristically unique surface and bottom topography provides a challenging test-bed for intercomparing the performance of all these model classes. Over the past decade a number of these existing ocean general circulation models have been in fact been adapted to the study of sub ice shelf cavity ocean circulation. A relatively recent review of these modeling activities is given by Williams et al. (1997).
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. © David Holland. All Rights Reserved. |
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