Open Boundary Condition for Circulation Models

Abstract

A persistant difficulty in modeling continental shelf and estuarine circulations is that associated with the correct specification of conditions on the open boundaries. This paper deals with the application of a new form of radiation condition on the open boundaries, which permits the mean subtidal and tidal forcing to be prescribed and, yet, allow transients generated inside the region to be transmitted outwards. A numerical model of shelf circulation is formulated, using vertically integrated equations, which accounts for tidal and transient wind forcing, as well as the effect of density gradients and the offshore large-scale oceanic circulation. The shelf model is dynamically linked to a storm model. The circulation model is applied to the Middle Atlantic Bight in a study of its response to a migratory storm superimposed on the sub–tidal and tidal circulation. The major estuaries of the region—Chesapeake Bay, Delaware Bay and Long Island Sound—are included in the domain, albeit at a resolution coarser than desirable. The model results are consistent with those of earlier observational and modeling studies.