Forced Shelf Wave Dynamics for a Discontinuous Shelf Width: Application to Vancouver Island

Abstract

Abstract The authors examine barotropic nondivergent shelf waves generated on an exponential continental shelf that has an abrupt change in width. Three types of forcing are considered: 1) a tidal period volume flux through a gap in the coastline located along the discontinuity, 2) an alongshore propagating wind stress over the continental shelf, and 3) an alongshore propagating perturbation in the streamfunction at the edge of the continental slope. Dimensional results for the linearized models are derived for the northwest coast of Vancouver Island, British Columbia, where the shelf abruptly widens into Queen Charlotte Sound. Because of the change in wave scales and numbers of shelf modes possible on either side of the coastline discontinuity, the response for the discontinuities width shelf differs markedly from that for a uniform width shelf. Results show that shelf wave energy generated by fortnightly tidal flow through the gap (or coastal strait) is radiated in a narrow “beam” across the broader por...