Low‐frequency current and temperature variability from Gulf Stream frontal eddies and atmospheric forcing along the southeast U.S. outer continental shelf

TLDR: In this article, low-frequency current and temperature time series from the outer shelf between Cape Canaveral, Florida, and Cape Romain, South Carolina, are compared with shipboard hydrographic data, satellite VHRR, coastal and buoy winds, and coastal sea level during the period from February to June 1980.

Abstract: Low-frequency current and temperature time series from the outer shelf between Cape Canaveral, Florida, and Cape Romain, South Carolina, are compared with shipboard hydrographic data, satellite VHRR, coastal and buoy winds, and coastal sea level during the period from February to June 1980. Low-frequency current and temperature variability along the shelf break was primarily produced by cyclonic, cold core Gulf Stream frontal eddies. These disturbances traveled to the north at speeds of 50 to 70 cm s−1 with periods of 5 to 9 days throughout the experiment and produced cold cyclonic perturbations of the northward mean flow and temperature fields over an along-shelf coherence scale of 100 km. Frontal eddies appear to be an important mechanism in the observed eastward transport of northward momentum and heat along the shelf edge. They also appear to play a key role in the transfer of eddy kinetic and potential energy back to the mean flow, which suggests an upstream formation region and shear-induced dissipation. Upwelling velocities of about 10−2 cm s−1 in the cold core provide the major source of new nutrients to the outer shelf. Subtidal flow variability at the 40-m isobath was a mixed response to Gulf Stream and wind forcing. Barotropic along-shelf current oscillations were coherent with the local winds and coastal sea level at periods of 3–4 and 10–12 days over along-shelf scales of 400 km with small phase lags, suggesting a nearly simultaneous frictional equilibrium response to coherent wind-induced sea level slopes.