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

Abstract

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.