Penetration of Buoyant Coastal Discharge onto the Continental Shelf: A Numerical Model Experiment

Abstract

Abstract Plumes of buoyant water produced by inflow from rivers and estuaries are common on the continental shelf. Typically they turn anticyclonically to flow alongshelf as buoyancy-driven coastal currents. During this passage, mixing with ambient shelf water gradually erodes the plume buoyancy so that its alongshelf penetration is finite. This paper addresses the extent of this penetration and how it is determined by fundamental dimensionless flow parameters. A three-dimensional numerical model is applied to an idealized flow regime. Ambient shelf conditions include tidal motion, but neither wind stress nor ambient alongshelf current. The alongshelf extent of penetration is evaluated after the plume reaches a stationary condition downshelf. A total of 66 model experiments are conducted, including variations in buoyant source and ambient shelf properties. Five dimensionless parameters determine the alongshelf and across-shelf penetration, the latter the coastal current width. The most critical of these i...