Inner shelf circulation patterns driven by synoptic weather systems on the South Carolina Coast

Abstract:

The meteorological forcing on the inner shelf of Long Bay, South Carolina (USA) has been analyzed using wind records extending over a period of 10 years. This analysis identified three synoptic systems classified as cold fronts, warm fronts and tropical storms. The typical temporal evolution of each system has been fully characterized statistically; the associated temporal evolution of the offshore, directional, spectral wave conditions have also been identified for the duration of each event. These typical wind and wave conditions are used to numerically investigate the response of the inner shelf. In addition, the influence of the curved coastline is examined. The numerical experiments were carried out using the ROMS and SWAN models of the Coupled Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) modeling system and the results are presented.

The results to-date suggest that, within the inner shelf a variability in the alongshore pressure gradient that is related to the alongshore variability of the relative angle between the wind forcing and the coastline. This coastline variability seems to affect the relative importance of the cross-shore / alongshore forcings creating different vertical structures of current at locations with different relative angle between wind forcing and coastline. Finally, the inclusion of the waves enhances the spatial differences observed for each case. These differences are explained in terms of momentum balance analysis.