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dc.contributor.authorCallaghan, Adrian H.
dc.contributor.authorDeane, Grant B.
dc.contributor.authorStokes, M. Dale
dc.contributor.authorWard, Brian
dc.date.accessioned2018-09-20T16:02:27Z
dc.date.available2018-09-20T16:02:27Z
dc.date.issued2012-09-01
dc.identifier.citationCallaghan, Adrian H. Deane, Grant B.; Stokes, M. Dale; Ward, Brian (2012). Observed variation in the decay time of oceanic whitecap foam. Journal of Geophysical Research: Oceans 117 ,
dc.identifier.issn0148-0227
dc.identifier.urihttp://hdl.handle.net/10379/10655
dc.description.abstractWhitecap foam decay times for 552 individual breaking waves determined from digital images of the sea surface are reported. The images had sub-centimeter pixel resolution and were acquired at frame rates between 3 and 6 frames per second at the Martha's Vineyard Coastal Observatory over a 10-day period in 2008, subdivided into 4 observation periods. Whitecap foam decay times for individual events varied between 0.2 s to 10.4 s across the entire data set. A systematic positive correlation between whitecap foam decay time and maximum whitecap foam patch area was found for each observation period. For a given whitecap size within each observation period, the decay times varied between a factor of 2 and 5, with the largest variation occurring during unsteady environmental forcing conditions. Within observation periods, bin-averaged decay times varied by up to a factor of 4 across the range of foam patch areas. Between observation periods, the effective whitecap foam decay time, which we define as the area-weighted mean decay time, varied by a factor of 3.4 between 1.4 s and 4.8 s. We found a weak correlation between decay times and individual event-averaged breaking wave speeds. The variation in the active breaking area across all 4 observation periods was small, indicating relatively uniform surface whitecap area generating potential. We speculate that the variation in the foam decay times may be due to (i) the effect of surfactants on bubble and foam stability, and (ii) differences between bubble plume characteristics caused by a variation in breaking wave type.
dc.publisherWiley-Blackwell
dc.relation.ispartofJournal of Geophysical Research: Oceans
dc.subjectsurface-active material
dc.subjectwave-field conditions
dc.subjectbreaking waves
dc.subjectsea-surface
dc.subjectcoverage
dc.subjectwater
dc.subjectfilms
dc.subjectdissipation
dc.subjectslicks
dc.subjectenergy
dc.titleObserved variation in the decay time of oceanic whitecap foam
dc.typeArticle
dc.identifier.doi10.1029/2012jc008147
dc.local.publishedsourcehttp://onlinelibrary.wiley.com/doi/10.1029/2012JC008147/pdf
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