Interaction of a slope eddy with the shelfbreak front in the Middle Atlantic Bight

Spring conditions at the shelf break in the Middle Atlantic Bight mark the transition period between the generally well-mixed shelf water in winter an d the highly stratified shelf conditions during summer. A high-resolution h ydrographic survey made during early May 1996 is used to describe the therm ohaline and velocity structure of the shelfbreak front. The front was stron gly affected by the presence of a slope eddy immediately offshore of the fr ont. The eddy, which had a diameter of 25 km. was anticyclonic with onshore /offshore flows of 0.2 m s(-1) on opposing sides. On the western side of th e eddy, where the flow seaward of the front was predominantly onshore, the front was very steep and the frontal jet was particularly strong, with maxi mum nearsurface velocities of 0.5 m s(-1). On the eastern side of the eddy, the front was drawn offshore and was much less steep, with near-surface ve locities of only 0.2 m s(-1). A surprising feature was the presence of a se cond jet over the foot of the front, shoreward of the main. surface-trapped jet. These observations suggest that eddies over the slope have a large im pact on shelfbreak frontal structure. and result in strong alongfront gradi ents within the frontal jet.