The University of Southampton
University of Southampton Institutional Repository

Aeration due to breaking waves. Part II: Fluxes

Aeration due to breaking waves. Part II: Fluxes
Aeration due to breaking waves. Part II: Fluxes
Measurements have recently been obtained of bubble concentrations at a coastal shelf-sea site. A simple model of the generation of persistent bubble clouds by wind waves as they break, and of the subsequent evolution of the clouds, is here developed that harnesses these measurements. Estimates are derived of the frequency of wave breaking, the volume of air entrained on cessation of breaking, and the rate of transfer of carbon dioxide between bubbles and water in the clouds. Bubble clouds are generated at an estimated rate, 50 x2(g/ l5)1/2, per unit sea surface area, where xis the dominant wave slope, or ratio of significant wave height Hs to energetically dominant wavelength l, and g is the acceleration due to gravity. Cloud generation contributes a term, 500 x4, to the active whitecap fraction. Entrainment distributes bubbles over a volume of equivalent hemispherical radius, 2Hs. The large-scale turbulence surviving breaking is insufficient to sustain bubbles—by opposing their buoyancy— to the largest size held stable while rising by surface tension. The bubble size distribution on cessation of breaking is instead predicted to fall off rapidly for bubbles in excess of a radius, am 5 7 3 1023( n2 l3/g)1/6, where n is the kinematic viscosity of seawater. At a (10 m) wind speed of 10 m s21 at the site, the volume of air entrained per unit area of sea surface—the upward displacement of the surface by bubbles—is estimated to be a factor of 3 times am on cessation of breaking. The transfer of carbon dioxide following breaking within the clouds is insignificant.
0022-3670
1019-1035
Graham, A.
e6591a0a-c11d-4436-8f5a-aebb09c97279
Graham, A.
e6591a0a-c11d-4436-8f5a-aebb09c97279

Graham, A. (2004) Aeration due to breaking waves. Part II: Fluxes. Journal of Physical Oceanography, 34 (5), 1019-1035. (doi:10.1175/1520-0485(2004)034<1008:ADTBWP>2.0.CO;2).

Record type: Article

Abstract

Measurements have recently been obtained of bubble concentrations at a coastal shelf-sea site. A simple model of the generation of persistent bubble clouds by wind waves as they break, and of the subsequent evolution of the clouds, is here developed that harnesses these measurements. Estimates are derived of the frequency of wave breaking, the volume of air entrained on cessation of breaking, and the rate of transfer of carbon dioxide between bubbles and water in the clouds. Bubble clouds are generated at an estimated rate, 50 x2(g/ l5)1/2, per unit sea surface area, where xis the dominant wave slope, or ratio of significant wave height Hs to energetically dominant wavelength l, and g is the acceleration due to gravity. Cloud generation contributes a term, 500 x4, to the active whitecap fraction. Entrainment distributes bubbles over a volume of equivalent hemispherical radius, 2Hs. The large-scale turbulence surviving breaking is insufficient to sustain bubbles—by opposing their buoyancy— to the largest size held stable while rising by surface tension. The bubble size distribution on cessation of breaking is instead predicted to fall off rapidly for bubbles in excess of a radius, am 5 7 3 1023( n2 l3/g)1/6, where n is the kinematic viscosity of seawater. At a (10 m) wind speed of 10 m s21 at the site, the volume of air entrained per unit area of sea surface—the upward displacement of the surface by bubbles—is estimated to be a factor of 3 times am on cessation of breaking. The transfer of carbon dioxide following breaking within the clouds is insignificant.

This record has no associated files available for download.

More information

Published date: 2004

Identifiers

Local EPrints ID: 9813
URI: http://eprints.soton.ac.uk/id/eprint/9813
ISSN: 0022-3670
PURE UUID: 74417b49-70cf-46e0-924b-9bc0d75da233

Catalogue record

Date deposited: 13 Oct 2004
Last modified: 15 Mar 2024 04:57

Export record

Altmetrics

Contributors

Author: A. Graham

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.

×