On the wintertime currents in the Florida Big Bend region

Abstract

Moored current meter records and hydrographic sections obtained during the winter over 3 years on the inner shelf in the northeastern Gulf of Mexico indicate the following. The along-isobath flow component is primarily in the upper water column and directed towards the Florida Peninsula (eastward). Near the bottom the flow is primarily and consistently diabathic and shoreward. The eastward upper flow does not appear to be locally driven, but results from an offshore pressure gradient, the cause of which is not identified. The shoreward, near-bottom flow appears to result from the local offshore wind and from estuarine processes resulting from the freshwater input of rivers and springs. The former appears to dominate in the late fall and early winter, and the latter to take over in late winter or early spring, when the wind abates or is from the east. The hydrographic sections indicate that vertically mixed conditions resulting from passing cold fronts do occur, but are relatively short lived and that estuarine hydrographic conditions tend to arise in the intervals between the passages of cold fronts. The proximity of the inertial period to the diurnal tidal periods (the latitude of our moored measurements ≈ 30°N) did not result in the observation of pronounced inertial oscillations. It did result in reversal of the sense of rotation of the K 1 and O 1 tidal ellipses as the bottom was approached. The latter is explained in terms of concepts and a model used in Weatherly et al. (1980)( Journal of Physical Oceanography 10, 297–300). © 1997 Elsevier Science Ltd