Laboratory study of circulation and upwelling in tidally-forced, shallow water island wakes

Topographic complexity on continental shelves is the catalyst that transforms the tide into secondary circulations that dominate vertical and cross-shelf mixing processes. Island wakes are an example that significantly influence material transport, but no mechanistic description of shallow, tidally-forced island wake formation exists. Novel and systematic laboratory experiments show here that island wake form is controlled by an unsteady stability parameter, with upwelling accurately predicted through an Ekman pumping model from the bed. The complex tapestry of upwelling and secondary circulations explain why island wakes are regions of greatly enhanced productivity, biodiversity and trophic aggregation.