Transport and fate of river discharge on the continental shelf of the Southeastern US

The authors have analyzed 8 years of wind and salinity data from a frontal zone in a region of the inner continental shelf off the southeastern United State. The changes in low-salinity water stored in the frontal zone have been parameterized by analyzing the monthly rate of change in freshwater content. When the rate of change in freshwater content was negative, the authors interpreted this as a loss of low-salinity water from the frontal zone. When this parameter was compared with seasonally averaged alongshore wind stress, the rate of loss was independent of the alongshore wind stress magnitude until threshold of about 0.1 dyne cm/sup -2/ was reached. Above the threshold there was a clear relationship between northward alongshore wind stress and rate of loss of freshwater from the inner shelf. Experimental evidence suggests that horizontal currents in the inner-shelf frontal zone have cyclonic shear with increasing depth. When wind stress is northward and offshore, near-shore low-salinity water is transported offshore by Ekman transport while near-bottom high-salinity water is transported shoreward.