Date of Award

Spring 2003

Project Type

Dissertation

Program or Major

Earth and Environmental Science - Oceanography

Degree Name

Doctor of Philosophy

First Advisor

Janet W Campbell

Abstract

In this dissertation a suite of satellite, discharge and in-situ measurements is used to explore the spatio-temporal distribution of terrestrial constituents in coastal environments. The covariance between riverine delivery of optically active constituents and the corresponding optical variability in neighboring coastal waters for the Mississippi and Orinoco Rivers is documented. From this work, satellite-based indices of fluvial influence (IFI), are developed which contain information on the spatial extent of riverine constituents in coastal waters. The IFI is defined as the correlation between time series of riverine discharge and an ocean color satellite-derived property in the region proximal to a river's discharge point.

These indices are employed to map the seasonal spatio-temporal variability of the Mississippi's sediment plume in the presence of discharge and wind stress fields. Here it is shown that: (1) the IFI techniques are useful for tracking terrestrial constituents delivered by the Mississippi's discharge; (2) coastal provinces dominated by fluvial influence have a different spatio-temporal distribution than those dominated by wind-driven resuspension, and thus these provinces can be discriminated, and (3) wind and discharge play different roles in the seasonal dynamics of the Mississippi's plume.

IFI techniques are used to isolate several individual river plumes in the northern Gulf of Mexico in which the relationship between in situ measurements of salinity and light absorption at 443nm were documented. Salinity vs. absorption relationships within the plumes were compared to modeled dissolved organic carbon fluxes from corresponding drainage basins. The results imply that variability in the flux of dissolved organic carbon across drainage basins imparts distinct variability in the optical characteristics of individual river plumes. Further, it is probable that ocean color sensors can help resolve this variability, and in fact have vast potential in aiding the understanding of the origin, persistence, trajectory and fate of riverine constituents in coastal waters.

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