Transient wind-driven upwelling in a submarine canyon: a process-oriented modeling study

A hydrodynamic model is employed to study flow near a submarine canyon during conditions of upwelling-favorable coastal winds. Findings reveal that up-canyon flow is the rapid geostrophic adjustment to barotropic pressure gradients establishing across the canyon. Stratification leads to the formation of a cyclonic eddy within the canyon, trapping neutrally buoyant matter, and limits the upwelling depth only when a strong seasonal pycnocline is located below shelf-break depth. Typical speeds of up-canyon flow are 10–30 cm/s. Constrained by the timescale of synoptic weather patterns (∼5 days), only stronger events (high upwelling index) can move slope water from a depth >300 m onto the continental shelf and close toward the coast, where it can be lifted into surface layers during a subsequent upwelling event.