Cross-Frontal Exchange in the Middle Atlantic Bight as Evidenced by Surface Drifters

Abstract

Surface drifters at 10 and 40 m are analyzed to assess cross-frontal exchange characteristics within the Middle Atlantic Bight. This Lagrangian analysis shows a shelfbreak jet characterized by strong and ubiquitous meandering. The drifters collectively demonstrate the continuity of the shelfbreak frontal jet from Georges Bank to Cape Hatteras. Along the length of the shelf break the drifters are detrained both onshore and offshore, yet offshore detrainment is predominant. The sites for offshore detrainment are distributed along the Bight, precluding the possibility that localized bathymetric features are the primary conduits for near-surface to mid-depth cross-frontal exchange. Finally, a strong seasonal asymmetry is noted in the drifter exchange pattern, with more offshore exchange in the winter than in the summer. However, the available data limits our interpretation of this feature.