A coastal ocean numerical model

Abstract

A coastal ocean model which, it is believed, is advanced beyond the current state of the art has been developed but is only in an early stage of application. Characteristics of the model include:

• a second moment turbulence closure model capable of accurate prediction of small scale turbulent mixing and derivative ocean features such as mixed layer temperature and depth.

• an algorithm which calculates the external (tidal) mode separately from the internal mode. The external mode, an essentially two-dimensional calculation, requires a short integrating time step whereas the costly, three-dimensional, internal mode can be executed with a long step. The result is a fully three-dimensional code which includes a free surface at no sacrifice in computer cost compared to rigid lid models.

• a “σ“ coordinate system with 20 levels in the vertical independent of depth. Thus, the environmentally important continental shelf, shelf bank and slope will be well resolved by the model. Furthermore, the model features increased resolution in the surface and bottom layers.

• coding deliberately designed for modern array processing computers. This is essential to three-dimensional ocean simulations requiring long integrations at tolerable cost.