The University of Southampton
University of Southampton Institutional Repository

Aeration due to breaking waves. Part I: bubble populations

Record type: Article

The population of bubbles produced by breaking waves in (10 m) winds of up to 12 m s?1 is analyzed using calibrated images from a vertical pencil-beam sonar system placed on the seabed near the Dutch coast. The structure in the images is parameterized, and the volumetric bubble backscatter is inverted to yield bubble concentrations. Data were obtained at three acoustic frequencies, with inversion effected by prescribing a bubble spectrum with two free variables, leaving a redundant measurement to test the robustness of the model. Median concentrations may in this way be obtained up to the sea surface. Measurements are multiply regressed on wind and dominant-wave variables. Bubbles penetrate to a depth of about a factor of 6??1 times the significant wave height Hs, where ? is the wave age, or ratio of dominant-wave phase speed to wind speed. The measured mean bubble radius decreases weakly with depth, unless waves are gently sloping, at about 5% m?1. At 0.4 m, the mean radius ranges from 30 to 80 ?m and is typically about two-thirds of the radius contributing most to void fraction. The total, depth-integrated surface area of the bubbles and their upward displacement of the sea surface, or “void displacement,” increase as wind speed to the powers 7 ± 1 and 8 ± 1, respectively, dependences ascribed to the preferential breaking of short, steep wind waves. It is estimated, on extrapolating trends, that the total bubble surface area on average is equal to that of the sea surface above them, and the mean void displacement is equal to the mean bubble radius, at a wind speed of about 15 m s?1.

Full text not available from this repository.

Citation

Graham, A., Woolf, D.K. and Hall, A.J. (2004) Aeration due to breaking waves. Part I: bubble populations Journal of Physical Oceanography, 34, (5), pp. 989-1007. (doi:10.1175/1520-0485(2004)034<0989:ADTBWP>2.0.CO;2).

More information

Published date: 2004

Identifiers

Local EPrints ID: 9814
URI: http://eprints.soton.ac.uk/id/eprint/9814
ISSN: 0022-3670
PURE UUID: bc845f98-f083-4d20-ae06-a3fffa33ad2d

Catalogue record

Date deposited: 12 Oct 2004
Last modified: 17 Jul 2017 17:08

Export record

Altmetrics


Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×