We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Tidal generation of large sub-mesoscale eddy dipoles.
- Authors
Callendar, W.; Klymak, J. M.; Foreman, M. G. G.
- Abstract
Numerical simulations of tidal flow past Cape St. James on the south tip of Haida Gwaii (Queen Charlotte Islands) are presented that indicate mesoscale dipoles are formed from coalescing tidal eddies. Observations in this region demonstrate robust eddy generation at the Cape, with the primary process being flow separation of buoyant or wind driven outflows forming large anti-cyclonic, negative potential vorticity, Haida Eddies. However, there are other times where dipoles are observed in satellites, indicating a source of positive potential vorticity must also be present. The simulations here build on previous work that implicates oscillating tidal flow past the cape in creating the positive vorticity. Small headland eddies of alternating vorticity are created each tide. During certain tidal cycles, the headland eddies coalesce and self organize in such a way as to create large >20-km diameter eddies that then self-advect into deep water. The self advection speed is faster than the beta drift of anti-cyclones, and the propagation direction appears to be more southerly than typical Haida Eddies, though the model contains no mean wind-driven flows. These eddies are smaller than Haida Eddies, but given their tidal origin, may represent a more consistent source of coastal water that is injected into the interior of the subpolar gyre.
- Subjects
HAIDA Gwaii (B.C.); BRITISH Columbia; TIDES; COMPUTER simulation; OCEANOGRAPHIC observations; BUOYANT ascent (Hydrodynamics); DIPOLE moments; VORTEX motion
- Publication
Ocean Science, 2011, Vol 7, Issue 4, p487
- ISSN
1812-0784
- Publication type
Article
- DOI
10.5194/os-7-487-2011