Cascading and the pathways of the key biogeochemical tracers in the Canadian Basin: from models and observations.

We explore dense water cascading (DWC; a type of bottom-trapped gravity current) on multi-decadal time scales using a pan-Arctic regional ocean-ice model. DWC is particularly important in the Arctic Ocean as the main mechanism of ventilation of interior waters when open ocean convection is blocked by strong density stratification. We identify the locations where the most intense DWC events occur and evaluate the associated cross-shelf mass, heat and salt fluxes. 

 

A detailed analysis of specific cascading sites around the Beaufort Gyre and adjacent regions is performed. We find that autumn upwelling of warm and saltier Atlantic waters on the shelf and subsequent cooling and mixing of uplifted waters trigger the cascading on the West Chukchi Sea shelf break. We also perform Lagragian particle tacking of low salinity Pacific waters originating at the surface in the Bering Strait; these waters are shown to be modified by brine rejection and cooling, and through subsequent mixing become dense enough to reach depths of 160-200m and below. We examine the role of cascading and shelf upwelling on the shelf waters transformation, pathways and spread of the biological important tracers (O18, Si., DIC snd DIN).