Florida current spin-off eddies

Abstract

Analysis of one year of near-surface current meter records from the narrow coastal zone inside the Florida Current off Boca Raton and Pompano, Florida, shows the occurrence of a large number of cyclonic current reversals that are not wind or tide induced. The reversals are accompanied by an advection of heat and salt into the coastal region and are interpreted as cyclonic eddies which spin off the western edge of the Florida Current and become entrained northward through the coastal waters. A kinematic model, combining a moving vortex pair with a uniform background current, is used to determine the spatial dimensions, phase speed, and circulation of spin-off eddies. Typical east-west dimensions are on the order of 10 km with the north-south lengths being 2 to 3 times greater. The characteristics translation speed is approximately 25 cm s −1 to the north. Energy spectra show maximum energy peaks that are believed to be associated with the occurrence of eddies at intervals of 1 to 2 days and lateral meandering of the Florida Current inshore front with several-day periods.