Date of Award

Spring 1980

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ocean & Earth Sciences

Program/Concentration

Oceanography

Committee Director

Ronald E. Johnson

Committee Member

Chester E. Grosch

Committee Member

George Ofelt

Committee Member

Carvel Blair

Abstract

A Lagrangian method utilizing clusters of four or five buoyed drogues is used to study the surface circulation and horizontal diffusion processes of the lower Chesapeake Bay. The study area encompasses some 160 km2 and includes the area north of Thimble Shoal Channel, southwest of Chesapeake Channel and west of the Chesapeake Bay Bridge and Tunnel. Eleven trials utilizing buoyed drogues were conducted in the time frame February to October, 1979. Four trials were interrupted when buoys entered neighboring channels or dispersed too far for tracking, so that a total of sixteen runs were completed on the eleven trial dates. The runs averaged five hours from drifter drop to recover, with the longest run nine hours. Eulerian surface current and speed data were taken at one at-anchor station over a tidal period of twelve and one-half hours.

The surface current, with local wind effect removed, is seen to be rotary, with the direction of rotation clockwise, and tidally dominated. It does not appear to be significantly influenced by, nor an influence on, the bordering channels with their dominant tidally reversing currents. A rotary current is not inconsistent with a tidally dominated wide estuary where Coriolis can be significant. The possibility of Kelvin and Poincare type wave motion is considered.

The horizontal diffusivity, as represented by Richardson's neighbor diffusivity concept, appears to confirm the applicability of the "4/3 power law" to the study area. The energy dissipation rate is consistent with the results of other investigators.

A need is recognized for a comprehensive Lagrangian-Eulerian diffusion/circulation field program that would permit simultaneous measurements of dye diffusion, drogue dispersion, currents, and tidal heights.

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DOI

10.25777/mrhz-b543

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