Coupling of the Middle and South Atlantic Bights by Forced Sea Level Oscillations

Abstract

The eastern United States continental margin is naturally divided by Cape Hatteras into the Middle and South Atlantic Bights. The margin depth profile is relatively uniform throughout the Middle Atlantic Bight, but in the South Atlantic Bight it bifurcates into inner and outer slope regions. Coastal tide gage records indicate that long period (1?2 weeks) sea level oscillations propagate southward as continental shelf waves in both Bights, thereby providing a coupling mechanism between the Bights. However, short-period (several days) oscillations appear to be confined to the south Atlantic Bight, and may result from backscattering of long-wave energy by the variable topography and the Gulf Stream. The coastal sea level short-period phase data are not easily attributable to monochromatic propagating waves; rather, it appears that wave group properties may lead to a more consistent explanation of the phases. Cross-shelf and longshelf wind stress components were both strongly coupled to sea level fluctuations for long periods; short-period motions were more closely associated with nonstatic atmospheric pressure fluctuations.