Topographic contraints on Rotating Stratified Throughflows Across Large Amplitude Topography

• Main Author: Jimenez-Urias, Miguel Angel
• Other Authors: Thompson, Luanne
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Asymmetry; Boundary layer; Idealized; Mixed layer fronts; Potential Vorticity; Topographic steering; Physical oceanography; Oceanography; Arctic; Greenland; Greenland-Scotland Ridge; Iceland; Nordic Seas; North Atlantic
• Online Access: http://hdl.handle.net/1773/44870

Thesis (Ph.D.)--University of Washington, 2019 The Atlantic inflow of warm saline waters that flow into the Nordic Seas is strongly steered by the Greenland-Scotland Ridge (GSR). Such flow is associated with the lateral exchange of watermasses between the North Atlantic and the Arctic Mediterranean and is part of the large scale overturning circulation of the ocean. This thesis examines, through the use of idealized, process-based modelling, aspects of the topographically locked Atlantic inflow that flows across the Iceland-Faroe Ridge, the widest and shallowest gap of the GSR. The effects of bottom topography on the instability, eddy-driven heat flux and overturning of a topographically locked top to bottom front is examined in Chapter 2. Central to this study is that the surface expression of the front presents lateral shear within the mixed layer, typical of wintertime conditions. We find the initial growth of surface mixed layer eddies is insensitive to topographic variations but during the finite amplitude phase of mixed layer instability, we find faster development of mesoscale eddies and stronger cross-front eddy heat flux in the cases where the frontal jet experiences the most destabilizing bottom topography of the three cases tested, with values comparable to the heat flux associated with the mean flow. Therefore, eddy dynamics over the IFR frontal region are important contributors to the heat exchanges between the North Atlantic and Nordic Seas, with bottom the topography playing a key role in determining the largest heat fluxes, whether the initial growth is dominated by mixed layer eddies, or mesoscale eddies. Chapter 3 examines the leading order balance that determine the transport pathways associated with throughflows across a symmetric, large amplitude ridge. The equilibrated circulation across the ridge is characterized by an anticyclonic boundary current associated with northward upslope transport and a cyclonic boundary current associated with north- ward downslope transport, with a strong ...