Stochastic boundary conditions for coastal flow modeling

Abstract

Recent high‐resolution radar data of surface velocity between the Florida Current and the coast allow us for the first time to deduce coastal boundary conditions for ocean models based on observations. A stochastic model is found to be a better choice for simulating properties of the observed vorticity than a model with deterministic boundary conditions. A stochastic model parameterizing boundary conditions is developed and embedded in a simple quasigeostrophic ocean model. Comparison of numerical simulations of western boundary flow with stochastic boundary conditions against simulations with traditional no‐slip and free‐slip conditions reveals significant differences in the formation of coherent mesoscale structures and the energetics of the western boundary current. Coherent structures such as dipoles and submesoscale vortices can be generated using stochastic boundary conditions. The boundary current variability becomes more energetic and “episodic” than quasi‐periodic circulation features in the simulations using the conventional boundary conditions.