6.7 Whitecap Fraction of Actively Breaking Waves: Toward a Database Applicable for Dynamic Processes in the Upper Ocean

Tuesday, 10 July 2012: 5:00 PM
Essex North (Westin Copley Place)
Magdalena D. Anguelova, NRL, Washington, DC; and P. A. Hwang
Manuscript (1.5 MB)

Handout (4.4 MB)

We have compiled a database of whitecap fraction W from satellites-borne microwave radiometric observations. These observations provide the total W including foam generated during active breaking of wind-driven waves and residual foam left behind by these breaking waves. Predictions of sea spray aerosol production and heat exchange use values of W. However, the whitecap fraction associated with the actively breaking waves WA is needed for dynamic air-sea processes in the upper ocean such as turbulent mixing, gas exchange, ocean ambient noise, and spray-mediated intensification of tropical storms. To parameterize such processes, a database of WA separate from W is needed. We have demonstrated such a separation is feasible by combining the Phillips concept of breaking wave statistics which connects WA with the energy dissipation rate of breaking waves and parametric estimates of energy dissipation from wave spectra measured from buoys. In this presentation, we describe the principle of the W versus WA separation, identify the parameters that affect the accuracy of our approach, present results for WA extracted from the satellite-based values of W for one year using buoy data in different geographical regions, and discuss the use of these regional data for extrapolation of this approach on a global scale.
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