Date of Award

Spring 2020

Project Type

Thesis

Program or Major

Earth Sciences

Degree Name

Master of Science

First Advisor

James Pringle

Second Advisor

Thomas Lippmann

Third Advisor

Gregory Chini

Abstract

Glacial troughs are flat-bottomed, steep-sided submarine valleys, which almost or entirely

incise the shelf, that significantly alter coastal circulation. A barotropic, linear, steady-state

model is used to quantify this alteration as a function of shelf geometry. These model results

demonstrate that troughs eject most of the shelf transport offshore to the slope. This offshore

ejection diminishes wind-driven alongshore transport downwave of the trough; downwave is

the direction of long coastal trapped wave propagation.

Offshore ejection is caused by bottom friction dissipating relative vorticity. Troughs

enhance offshore ejection by generating relative vorticity. This is because linear flows on an

f-plane (used in this model) follow isobaths to first order. Troughs on the shelf generate

relative vorticity through two means: the curving isobaths, which define the trough, steer

flows, creating a “flow curvature,” and the narrowed shelf, between the coast and trough,

accelerates the flow and creates a “flow shear.” The relative importance of these two trough

induced mechanisms and a quantification of the net ejection is found with this model.

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