Skidaway Institute of Oceanography
Research About US Education Faculty Publications R/V Savannah

Jackson O. Blanton (Emeritus). Transport and mixing in shallow coastal waters and estuaries
Dana K. Savidge (Associate). Shelf circulation and deep ocean western boundary currents.
Catherine R. Edwards (Assistant).

James R. Nelson (Associate Emeritus). Coastal Ocean Optics and Observatories

Physical Oceanographers investigate circulation in the open ocean, on continental shelves and in estuaries, and the processes and forces affecting that circulation. This is done using observations and analytical or numerical modeling. At SkIO, we use a wide variety of observational techniques, including collecting data from ships, from moored instrumentation or real-time semi-permanent intrumentation on shelf towers, and from remote observations - satellites and shore-mounted radars. Modeling of important processes is a vital component, accomplished through collaborations with investigators at other institutions.

Starting at the shelf edge, SkIO scientists study Gulf Stream variability. Gulf Stream meandering upwells cold nutrient rich water onto the outer shelf along the South Atlantic Bight, supporting large quantities of new production on the shelf. Outer and midshelf responses to wind, wave and Gulf Stream forcing affect the alongshelf and crossshelf transport of nutrients, phytoplankton, and zooplankton. These transports are important to fish life histories, particularly in the early planktonic egg and larval stages of shelf edge spawning, estuarine-dependent, commercially or recreationally important species. Tides on the Georgia and South Carolina coasts are particularly strong, and are an important component of shelf circulation. On the inner shelf, buoyancy effects from freshwater runoff and large air-sea heat fluxes become important as well. Friction and the effects of bathymetry become especially important in the estuaries and tidal marshes in and around our extensive barrier islands.

In addition to studies along the SAB coastline, SkIO physical oceanographers investigate circulation in a variety of locations around the world, including the Great Lakes, Cape Hatteras North Carolina, the North Atlantic, Portugal, and the west Antarctic Peninsula. We support one of the longest nearly continuously operating coastal observatories in the world, which now includes a recently installed benthic observatory to examine exchange between the water column the underlying permeable sand ocean bottom. We are utilizing a variety of new and developing instrumentation, including a SeaSciences Acrobat (a towed undulating vehicle carrying CTD and nitrate sampler), an RDI 600 kHz five-beam ADCP (VADCP) for examining turbulent stuctures at the midshelf, and a shore-mounted WERA HF-radar system, for measuring currents, waves, and winds all across the Georgia shelf. Satelite imagery is routinely collected and ground-truthed through in-situ optical instrumentation, deployed from ships and longer-term from the towers.

Recent examples of projects can be viewed by clicking one of the topics highlighted below.



WERA HF-radar



In-situ satellite calibration project

Estuarine Circulation -- The competing effects of density and tidally-driven circulation in estuaries. Analyses of data in several of Georgia's coastal plain estuaries have provided information on the response of the density structure to forcing due to wind on the continental shelf. A particular focus deals with secondary circulation in curving channels.

Tidal Asymmetry -- Factors that distort tidal currents in estuaries and tidal creeks. The distortion of the M2 tide in shallow estuaries plays an important role in sediment and salt transport. Factors such as friction and channel morphology generate shallow water overtides such as M4 and M6. When these are added to the M2 tidal current, maximum ebb and flood are shifted closer to high or low water resulting in a tidal current that is distorted from the M2 component. Whether the shift goes toward low or high water depends on the hyposometric curve of the surrounding salt marshes.

Estuarine-Ocean Exchange -- Processes that govern exchange of water between estuaries and oceans.
Research is being focused on the net transport through tidal inlets and the controlling dynamics. Present studies suggest that axial transport of water and salt is achieved through a competition of tidally-induced and discharge-induced flows. In a multiple inlet system sych as found in Georgia, this competition varies from inlet to inlet. Interannual cariations in freshwater discharge to Georfia estuaries greatly affect the inland penetration of salt to Georgia's estuarine system.

Larval Transport -- Circulation that affects the transport of larvae on the continental shelf and in estuaries.
A 4-year study, sponsored jointly by South Carolina and Georgia Sea Grant Programs, has been completed on oceanographic factors affecting the transport of larvae from the continental shelf to estuarine nursey grounds (GA Sea Grant Final Report, Key Factors Influencing Transport of White Shrimp Postlarvae in Southeastern U.S. Estuaries). A combination of field studies and numerical simulations revealed the importance of the fortnightly tidal cycle and continental shelf winds on creating conditions favorable for larval transport through tidal inlets.

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