FY 1980

Surface trajectory model for continental shelf waters

Overland, J.E., and J.A. Galt

In Proc. Joint IOC/WMO Seminar on Oceanographic Products and the IGOSS Data Processing and Services System, Intergovernmental Oceanographic Commission Workshop Rep. 17, Moscow, USSR, 2–6 April 1979, 323–341 (1979)

A comprehensive surface trajectory model has been developed for the northeastern Gulf of Alaska continental shelf that includes three elements: surface wind drift, barotropic currents (wind driven), and baroclinic currents (density driven). To provide regional winds, previous synoptic climatologies were specialized for the segment in proximity to the high coastal mountains. Currents are provided by a finite element diagnostic shelf circulation model, which assumes that currents are a combination of geostrophic and Ekman flows as modified by bathymetry. The diagnostic model is decomposed into density-driven and wind-driven components. A set of barotropic current patterns were developed to correspond to each one of the weather types of the synoptic climatology. In a trajectory scenario, a sequence of weather types are selected from synoptic weather charts, the magnitude of the pattern is scaled by a single anemometer record, and the density fields are provided by recent hydrographic surveys. Dispersion of trajectories in the Gulf of Alaska is quite large and bimodal. Temporal variation of the wind plays an important role as well as the spatial variation of the relative magnitude of wind-driven and density-driven drift.