A new open ocean, hybrid coordinate primitive equation model

A new open ocean hybrid coordinate primitive equation model based on the standard model of Bryan and Cox has been developed for regional applications. Several issues of regional modeling are addressed, including: model initialization; open boundary conditions; and horizontal filtering on sloping coordinate surfaces. The applicability of the new regional model for applications to mesoscale ocean modeling is demonstrated. The open boundary conditions are calibrated against a primitive equation reference ocean for three realistic flow regimes. The analytic solution for f-plane flow over a gaussian bump with constant stratification is reproduced. A comparison is made between the regional primitive equation model and the Harvard Open Ocean Quasigeostrophic model for a simulated mesoscale eddy field for a 30 day simulation. Differences in the two model calculations are attributed to model physics and not numerics or representations of the model variables.