Effects of western boundary current dynamics on the internal wave field of the Southeast Florida shelf

Shelf sea internal wave fields are typically highly variable and dominated by wind and tidal forces. However this is not necessarily true for outer shelf regions or very narrow shelves where remote physical processes originating over the slope or deep ocean may exert a strong influence on the internal wave climate. During the summers of 2003 and 2004, observational studies were conducted to examine the effects of a western boundary current (the Florida Current), tides, and wind on the mean currents and internal wave field on the outer Southeast Florida shelf. Wavelet analyses of nonstationary shelf currents coupled with altimetry images of the Straits of Florida reveal the strong influence of Florida Current fluctuations on outer shelf flows. Local winds were found to be a small factor in flows on the outer shelf region and tidal forcing (diurnal and semidiurnal) accounted for less than a third of the total barotropic variance. High-frequency internal waves dominate the internal wave field and result in bottom-intensified currents and strong shoreward mass transport. We present evidence that suggests that the Florida Current plays as large a role in the determination of the high-frequency internal wave field as tidal forces. These observations and analyses show that it is necessary to include the forcing from the Florida Current meanders and instabilities in order to predict accurately the episodic nature of the internal wave field on the Southeast Florida shelf.