Lower-atmosphere upper-ocean interactions: the influences of breaking waves

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Date
2015-10-29Author
Scanlon, Brian
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Abstract
Wave breaking at the ocean surface is an important process for air-sea
exchange. Whitecaps are visual sea surface signatures of breaking waves.
By measuring the fractional coverage of whitecaps on the sea surface, it is
possible to quantify wave breaking. This thesis comprises of three distinctive
pieces of research. I compare model simulations of sea surface temperature
to high resolution observations for three unique cases. The model runs
over a daily cycle using a 1-dimensional 2nd moment closure turbulence
scheme with the inclusion of a wave breaking model. The comparisons reveal
poor performance when the wave breaking model is included. Subsequently,
attempts to improve on our understanding of wave breaking were made. I
developed a technique for estimating whitecap coverage estimates of both
actively breaking (stage A) waves, and maturing (stage B) foam. The Spatial
Separation of Whitecap Pixels (SSWP) allows for accurate distinguishing
of stage A and stage B whitecap regions by manually evaluating the pixel
intensity, location (with respect to the crest of the wave), texture and shape of
a given whitecap region. Finally, measured WA and overall whitecap coverage
(WT = WA +WB) for the North Atlantic dataset were then compared with
modeled estimates of whitecap coverage, derived using a semi empirical
formula and various wave-field model parameters. High resolution model
estimates of the wave-field are provided by the European Center for Medium
Range Weather Forecasting (ECMWF) Wave Model (WAM). Results reveal
good performance between WA and modeled generated WT for specific tuning
values, which are provided.