Topographic Preconditioning of Open-Ocean Deep Convection

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Abstract
Evidence for oceanic convection over Maud Rise in the Weddell Sea suggests that bottom topography may select the location and scale of deep convecting oceanic chimneys forced by seasonal large-scale atmospheric cooling. In this paper, the role of bottom topography in open-mean deep convection is studied using an idealized three-dimensional primitive equation model. A barotropic mean flow impinges on a Gaussian-shaped seamount in a stratified domain generating a Taylor cap (a region of topographically trapped fluid). Uniform surface cooling is applied throughout the domain. When the Taylor cap is tall enough to interact with the surface mixed layer, the local isolation from the advection of heat by the mean flow forms a conduit into the deep water. Convection within this region is significantly enhanced relative to ambient levels away from the seamount and to similar numerical simulations performed without bottom topography. Given uniform background stratification, domed isopycnals are not importa... Abstract Evidence for oceanic convection over Maud Rise in the Weddell Sea suggests that bottom topography may select the location and scale of deep convecting oceanic chimneys forced by seasonal large-scale atmospheric cooling. In this paper, the role of bottom topography in open-mean deep convection is studied using an idealized three-dimensional primitive equation model. A barotropic mean flow impinges on a Gaussian-shaped seamount in a stratified domain generating a Taylor cap (a region of topographically trapped fluid). Uniform surface cooling is applied throughout the domain. When the Taylor cap is tall enough to interact with the surface mixed layer, the local isolation from the advection of heat by the mean flow forms a conduit into the deep water. Convection within this region is significantly enhanced relative to ambient levels away from the seamount and to similar numerical simulations performed without bottom topography. Given uniform background stratification, domed isopycnals are not importa...

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