Subtidal Dynamics at Cape-Associated Shoals

The influence on subtidal currents by winds, waves and the Florida Current were investigated within the inner-shelf environment adjacent to Cape Canaveral, Florida. The study focused on two sites that represent cape-associated shoals (5-15m water depth) for a northern promontory (False Cape) and a southern promontory (Cape Canaveral proper). At both sites, acoustic Doppler current profilers (ADCPs) were moored on either side (seaward and landward) of a shoal, for a total of 4 ADCP locations. Spectral analyses showed a semidiurnal signal in the velocities and water levels at all locations, consistent with tidal influence. However, the diurnal signal visible in the water level was not evident in the currents. A complex empirical orthogonal function (CEOF) analysis provided the dominant spatial and temporal structure of the currents at all 4 locations. Mode 1 accounted for the bulk of the variance (92%) as compared to mode 2 (5%). The vertical profile of the currents was unidirectional at all locations as for modes 1 and 2. Wavelet coherence analyses showed that water level changes were highly coherent over mode 1 velocity oscillations, especially at ~6-7 day periods. Further analyses showed that, in turn, sea level oscillations at Cape Canaveral were influenced by variations in the Florida Current transport.