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Observations on the evolution of tidal vorticity at a stratified deep water headland
Author(s) -
Pawlak G.,
MacCready P.,
Edwards K. A.,
McCabe R.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018092
Subject(s) - baroclinity , barotropic fluid , geology , headland , vorticity , drifter , potential vorticity , eddy , oceanography , vortex , geophysics , meteorology , turbulence , physics , shore , lagrangian , mathematical physics
The lifespan of a barotropic tidal eddy generated by flow around a coastal headland in deep (∼200 m) stratified water is examined. Field observations recorded the evolution of the flood tide eddy from its generation, through the eddy release at the turn of the tide, until its dissipation during subsequent tidal cycles. Ship‐based acoustic profiling reveals vortical structure that extends throughout the flow depth. Tracks from subsurface drifters from successive days indicated that flow structure was repeatable. Vorticity decay times, estimated from combined set of drifter tracks, are less than a tidal period. These are significantly shorter than simple estimates using boundary friction would imply, and it is suggested that baroclinic mechanisms associated with tilted vorticity in the deep stratified flow over the sloping headland may play a significant role in the dissipation of vorticity.