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Vorticity generation by short‐crested wave breaking
Author(s) -
Clark David B.,
Elgar Steve,
Raubenheimer Britt
Publication year - 2012
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 - 10.1029/2012gl054034
Subject(s) - vorticity , breaking wave , positive vorticity advection , potential vorticity , crest , advection , vortex , physics , eddy , vorticity equation , mechanics , geology , geophysics , wave propagation , turbulence , optics , quantum mechanics
Eddies and vortices associated with breaking waves rapidly disperse pollution, nutrients, and terrestrial material along the coast. Although theory and numerical models suggest that vorticity is generated near the ends of a breaking wave crest, this hypothesis has not been tested in the field. Here we report the first observations of wave‐generated vertical vorticity (e.g., horizontal eddies), and find that individual short‐crested breaking waves generate significant vorticity [ O (0.01 s −1 )] in the surfzone. Left‐ and right‐handed wave ends generate vorticity of opposite sign, consistent with theory. In contrast to theory, the observed vorticity also increases inside the breaking crest, possibly owing to onshore advection of vorticity generated at previous stages of breaking or from the shape of the breaking region. Short‐crested breaking transferred energy from incident waves to lower frequency rotational motions that are a primary mechanism for dispersion near the shoreline.