Observing system depiction of circulation on the SE US coastal ocean

Abstract

A series of observing platforms deployed between Cape Henry, VA and Cape Canaveral, FL provide multi-year records of winds, surface currents, current profiles and vertical stratification at a number of locations on the shallow southeast US continental shelf and are used to construct a seasonal circulation pattern. Upwelling-favorable winds and circulation in summer promote poleward shelf transport and stratification in summertime, assisted near the shelfbreak by the influence of the Gulf Stream. Downwelling-favorable winds and circulation dominate in fall and winter, but mean alongshore currents are weak and cross-shelf exchange is strong relative to the alongshore flow. Convection driven by thermal cooling over the shallowly sloping shelf is explored as a potentially important component of the observed wintertime circulation. This observing system-based Eulerian depiction of the circulation described above is compared with previous published seasonal circulation patterns and Lagrangian representations from drifter and modeling studies. The consistency of the results over the domain is considered to assess the adequacy of the observing system to resolve subregional-scale circulation features.