On reducing the slope parameter in terrain-following numerical ocean models
Abstract
Sigma coordinate ocean models, such as the Princeton Ocean Model, are a type of terrain-following model, which are
currently being used in regions with large topographic variability such as entire ocean basins, shelf breaks, continental
shelves, estuaries and bays. The main concern when using a terrain-following ocean model is to reduce the pressure gradient
force error (PGFE). Regardless of the method of calculation of the pressure gradient, the PGFE will not be reduced
to an acceptable value without first reducing the slope parameter, defined by the absolute value of the ratio of the difference
between two adjacent cell depths and their mean depth. Here two methods for reducing the slope parameter are compared:
a traditional two-dimensional smoothing with Gaussian filters and an alternative one-dimensional robust direct iterative
technique. While both methods efficiently smooth the bottom topography so that the pressure gradient errors are reduced
to acceptable levels, the alternative method is shown to have a unique advantage of maintaining coastline irregularities,
continental shelves, and relative maxima such as seamounts and islands.
Description
The article of record as published may be found at http://dx.doi.org/10.1016/j.ocemod.2006.01.003
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