Shelf-slope frontal structure and cross-shelf exchange at the New England shelf-break

Temperature and current data derived from the SEEP—I array moored on the New England continental margin during 1983–1984 are used to study the structure and motion of the shelf-slope water front and the cross-shelf exchange of heat. During the winter frontal motion is associated primarily with wind-driven Ekman forcing across the shelf-break. The foot of the front undergoes 10–20 km cross-shelf excursions which are not correlated with current fluctuations over the slope. The cross-shelf eddy flux of heat has a large variance but zero mean. During the summer frontal displacements diminish as does the wind stress. As the seasonal thermocline develops shelf and slope regions become connected by isopycnal surfaces. This appears to facilitate diffusive exchange of shelf and slope water and the formation of submesoscale eddies at the frontal boundary. As the thermocline deepens late in the summer there appears to be an increase in the eddy flux of heat across the front from the slope to the deep shelf water. In the autumn intrusions of slope water are observed which may be related to a surface convergence and sinking along the front associated with geostrophic adjustment following a mixing event. During the year-long deployment one warm-core ring passed through the SEEP—I array. Little of the heat flux observed over the slope penetrated onto the shelf.