Field measurements and scaling of ocean surface wave‐breaking statistics. Issue 12 (17th June 2013)

• Record Type: Journal Article
• Authors: Sutherland, Peter; Melville, W. Kendall
• Is Part Of: Geophysical research letters. Volume 40:Issue 12(2013:Jun.)
• Page Start: 3074
• Page End: 3079
• Publication Date: 2013-06-17
• Subjects: breaking waves -- whitecap -- infrared -- upper ocean turbulence -- dissipation -- stereo; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/grl.50584
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract : [1] Deep‐water breaking waves provide a mechanism for mass, momentum, and energy transfer between the atmosphere and ocean. Microscale breaking is particularly important, but notoriously difficult to measure in the field. In this paper, measurements from a new technique, using a stereo pair of long‐wave infrared cameras to reconstruct the sea surface shape and velocity field, are presented. Breakers are detected using an image texture‐based algorithm and then tracked on the reconstructed surface. These waves range from large air‐entraining breakers to microbreakers that are undetectable by traditional visible video‐based techniques. This allows measurements of breaker length distributions, Λ( c ), that extend to velocities near the gravity‐capillary transition. These distributions are compared with measurements from the literature and from visible video imagery. A nondimensional scaling is proposed which collapses Λ( c ). Finally, estimates of energy dissipation and stress based on Λ( c ) are found to agree well with wave energy dissipation and wind stress models. Key Points: New technique measuring wave‐breaking at sea using stereo IR image texture Crest length distribution measured for non‐air‐entraining microscale breakers Successful nondimensional scaling of the breaker crest length distribution