Spin-up and the effects of a submarine canyon: Applications to upwelling in Astoria Canyon

A parameterization for the on-shelf mass flux induced by upwelling through a shelf break submarine canyon is estimated by laboratory spin-up experiments. We determine the effects of a submarine canyon on flow evolution implicitly by measuring the topographic drag force in the context of a heuristic model. Trials were performed across a range of values for the shelf break velocity, Coriolis frequency, and buoyancy frequency. Assuming the drag force within the canyon is balanced locally by rotation, we propose a parameterization for upwelling through a canyon provided that the Coriolis frequency, buoyancy frequency, shelf break velocity, and canyon dimensions at the shelf break depth are known. We use our results to compare wind-forced and canyon-forced upwelling over Astoria Canyon off the coast of Washington State. The analysis suggests that canyon-forced upwelling through Astoria Canyon is of equal importance to wind-forced upwelling directly above it on seasonal scales.