Date of Award

Winter 1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ocean & Earth Sciences

Program/Concentration

Oceanography

Committee Director

Larry P. Atkinson

Committee Member

Gabriel T. Csanady

Committee Member

John M. Klinck

Committee Member

Jackson O. Blanton

Abstract

The circulation of water over the shelf of the southeastern United States was examined during the Fall Removal Experiment from late October to early November 1987. A steady state, two-dimensional analytical model of wind and density driven flow was used to study the relative importance of driving forces in shelf circulation, fate of freshwater and cross-shelf exchange processes. The inner and middle shelf mean circulation was found to be driven by four major components: (1) longshore wind, (2) longshore pressure gradient, (3) onshore wind and (4) cross-shelf density gradient including freshwater influx. Wind stress was the primary driving force for shelf circulation Southward wind stress produced a southward current with an embedded coastal jet, while weak wind stress reduced the jet strength and produced northward currents in the middle shelf. Strong southwestward wind events transported low salinity waters, from rivers in the central part of the South Atlantic Bight, southward to Cape Canaveral in a narrow baroclinic zone near the coast. Inner shelf fronts were produced by freshwater runoff. Downwelling favorable wind narrowed the baroclinic zone, inside of which a strong coastal jet developed. The runoff-induced residual circulation made a generally weak contribution to the mean flow field. Freshwater was mainly advected through the inner shelf off Savannah and Brunswick by longshore transport and through the middle shelf between Brunswick and St. Augustine sections by cross-shelf transport. Freshwater transport estimates showed that about 10% of the freshwater input off Savannah arrived at the Cape Canaveral section and a major portion of the remaining freshwater left the shelf region by offshore transport. About 30% of the freshwater flowing into the region was temporarily stored there. Cross-shelf transport was especially important during weaker winds. Salinity was used as conservative property for the calculation of the horizontal diffusion coefficient. The cross-shelf, and 107 cm2s-1 on the middle shelf locations. Most shelf regions showed dominant advective cross-shelf transport, while in frontal zone between Savannah and Brunswick sections there was an increase of diffusive cross-shelf transport. Current meter observations and surface distributions of tritium originating from the Savannah River confirmed the above analytical model and dynamical considerations.

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DOI

10.25777/13dp-k117

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