Three-dimensional seasonal-mean circulation and hydrography on the eastern Scotian Shelf

Abstract

A three-dimensional nonlinear finite element model with an advanced turbulence scheme is used in conjunction with historical current, temperature, and salinity observations to describe seasonal-mean circulation and hydrography on the eastern Scotian Shelf (ESS). The model solutions consist of density-, wind-, and boundary-driven currents, and associated elevation, hydrographic, and turbulence fields. The M 2 and K 1 tides are simultaneously computed to include the effects of tidally induced turbulent mixing and bottom friction, and tidal rectification. The circulation is dominated by surface-intensified baroclinic nearshore and shelf-break currents, both directed southwestward with prominent seasonal and alongshelf changes. These currents are primarily associated with the equatorward inflow of relatively fresh water from the Gulf of St. Lawrence and Newfoundland Shelf/Slope. Pronounced and persistent influences of outer-shelf banks, inner-shelf basins, and cross-shelf channels are evident in the circulation fields. In particular, the Sable Gully features a year-round cyclonic partial gyre, with a net onshore flow that is greatest in spring. A relatively strong anticyclonic gyre over Sable/Western Bank contrasts a weak partial gyre over Banquereau Bank. The model solutions are in approximate agreement with observed transports and currents for the primary flow features.