Glacial Troughs Enhance Shelf/Slope Exchange in the Barotropic Limit

Abstract

AbstractGlacial troughs are flat‐bottomed, steep‐sided submarine valleys that incise the shelf and significantly alter coastal circulation. We examine how these features drive exchange between the shelf and the slope in the barotropic and linear limits. When the alongshore flow is in the Kelvin‐wave (downwave/downwelling favorable) direction, the troughs move transport from the shelf upwave of the trough to the slope downwave of the trough, diminishing wind‐driven alongshore transport on the shelf downwave of the trough. Conversely, when the alongshore flow is against the Kelvin wave direction (upwave/upwelling favorable), the troughs move transport from the slope downwave of the trough to the shelf upwave of the trough. These cross‐shelf flows are driven by the acceleration and curvature of the flows induced by the narrowing and turning isobaths around the trough, and the bottom friction experienced by these accelerated flows. These dynamics are quantified by examining the along‐isobath evolution of potential vorticity in the model's limits.