Circulation & Exchange Within Shelf & Estuarine Waters Driven by the Atmosphere, Tides and Buoyancy

摘要

The proximity of human populations to the coast renders the studies of the coastal ocean important due to impacts by natural hazards, environmental management and material transport. This thesis will quantify the impacts of the atmosphere, tides and buoyancy forces in Rhode Island Sound (RIS) and Narragansett Bay (NB) at a variety of scales. Observational analysis and numerical modeling provide comprehensive tools to study resonance between the atmosphere and ocean beneath synoptic storm systems; to describe circulation in RIS; and to study the effect of tides on stratification in NB.;The characterization of the shallow shelf circulation under various forcing mechanisms provides information useful for hazard monitoring and environmental management. The study of momentum propagation over the East Coast continental shelf is discussed in Chapter 1. We determine the role of atmospheric pressure in creating high frequency surface gravity waves extending over a large geographic range. We find that shallow water waves are generated near the continental shelf break under long-lived squall lines.;Buoyancy, tides and wind driven circulation influencing RIS circulation and hydrography are examined using observations in Chapter 2. We find that the largest contributor to circulation are tides and the largest controller of stratification is solar insolation. At monthly time-scales we find a cyclonic coastal current present along the periphery of RIS, enhanced during the summer as a result of baroclinic and barotropic pressure gradients. During the winter the coastal current is reduced and, in some areas, not detectible. The reduction is thought to be caused by smaller baroclinic forces and barotropic forces that oppose the cyclonic circulation.;Chapter 3 expands beyond the spatial-temporal limitations of data moorings within NB by using numerical hydrodynamic models to reveal 4-D aspects of estuary dynamics. We find that much of NB has a maximum stratification during low or high tide resulting from a combination of straining, advection and mixing. The predicted tidal change in stratification is confirmed by observations from buoys located in NB.;The coastal area of New England, an area of great economic, recreational, and environmental importance, is an ideal area to study contemporary hydrographic and dynamic processes. This dissertation applies innovative analytical and numerical techniques to investigate the relative roles of atmospheric, buoyancy, and tidal forcing in determining circulation in the shallow shelf sea of RIS and in the NB estuary.