Near-Bottom Temperature and Current Variability over the Miami Slope and Terrace

Temperature and current data sets from the Miami Continental Slope and Terrace regions along southeast Florida are summarized to show the temporal and spatial variability of near-bottom waters with temperatures ≤10°C (defined as the cold water source: CWS). The CWS is generally found offshore of the 100- to 300-m isobaths. The annual mean intersection depths of the 10, 9, and 8°C isotherms with the bottom are approximately 200, 250, and 350 m, respectively. The most pronounced temperature and current fluctuations occur within a period band of 2 days to 2 weeks and are associated with horizontal wave-like meandering and eddy shedding. For the 10 and 9°C isotherms these oscillations produce excursions of up to 190 m in the vertical and 6 km in the horizontal. Displacements of the 8°C isotherm are much greater. Seasonal upwelling (downwelling) of cooler (warmer) waters onto the Terrace occur in the summer (winter); they are associated with the annual transport cycle of the Florida Current. Currents over the Slope and Terrace are highly variable with standard deviations several times the mean. Current vectors are primarily aligned with the isobaths. Near-bottom currents are dominated by reversals occurring with tidal to 2-week periods and amplitudes of ±20 cm/sec. The mean near-bottom current is weak (3.5 cm/sec) and to the north. Near-surface and inshore currents have speeds ranging from 50 to 150 cm/sec to the north and frequently reverse to the south with speeds up to about 50 cm/sec.