The Evolution of Density-Driven Circulation over Sloping Bottom Topography

Abstract

Abstract The short timescale temporal evolution of buoyancy-driven coastal flow over sloping bottom topography is examined using a two-dimensional, vertically averaged numerical model. Winter shelf circulation driven by a coastal “point source” buoyancy flux is modeled by initiating a coastal outflow with density anomaly ϵ into well-mixed shelf water. The nonlinear interaction between the time-varying velocity and density field is represented by an advection-diffusion equation. Three cases are discussed: that of a buoyant (ϵ 0) outflow. Results are similar to observations from well-mixed shelf areas and show that density-topography interactions are capable of substantially influencing coastal circulation. A negative (buoyant) coastal buoyancy flux is shown to generate alongshore motion with relatively small cross-shelf transport. Conversely, positive (dense) coastal buoyancy flux is shown to generate flow that travels across isobaths to initiate an...