Ocean Modeling and Parameterization

The realism of large-scale numerical ocean models has improved dramatically in recent years, in part because modern computers permit a more faithful representation of the differential equations by their algebraic analogues. Equally significant, if not more so, has been the improved understanding of physical processes on space and time scales smaller than those that can be represented in such models. Some of the most challenging issues remaining in ocean modelling are associated with parameterising the effects of these high-frequency, small-spatial-scale processes. At the present time, the success of any large-scale numerical simulation depends directly on the choices that are made for the parameterisation of various subgrid processes. These choices are often constrained by the overall model architecture and may be more or less natural to the particular model design. A good understanding of parameterisations and their impact on the modelled ocean circulations is crucial to the large international projects currently seeking to achieve global simulations. §In parallel, several large observational programs are underway, both from space and in situ, dealing with the short and long time scales. These observations are in turn leading to improvements in available parameterisations.