Modelling Internal Tides in the Strait of Canso

A three-dimensional regional circulation model is used to investigate the internal M2 tide structure in the Strait of Canso located in eastern Nova Scotia, Canada. The embayment, an active shipping port, was found to have M2 baroclinic velocities occasionally reaching 0.15 m s−1 and typically faster than the barotropic tide. An internal tide spatial structure develops, characterized by the first vertical mode, and highly sensitive to the details of stratification. A region near the mouth of the Strait, with a strong cross-bathymetry barotropic flow was identified as the main generating site. The regular “canyon-like” features of the Strait concentrate the energy towards the bottom and head and, under favourable conditions, reflect energy from the head, forming a standing wave. The modelling study found that, although some internal tide is generated year-round, only summer stratification conditions were favourable for standing wave development because of both increased internal energy levels and longer wavelengths capable of transporting the energy farther up the Strait. A balanced internal energy budget for the area highlights a tendency towards local dissipation and enhanced mixing rates. Persistent convection cells and upwelling zones suggest possible impacts on biological activity, sediment, and oil spill dynamics in the region. The findings are validated with current meter and water level observations.