Spectra of Ocean Noise Generated by Breaking Wind Waves

2000 ◽  
Vol 46 (2) ◽  
pp. 195
Author(s):  
G. A. Postnov
Keyword(s):  
Wind Waves ◽  
Breaking Wind Waves ◽  
Ocean Noise

On the clouds of bubbles formed by breaking wind-waves in deep water, and their role in air-sea gas transfer

1982 ◽  
Vol 304 (1483) ◽  
pp. 155-210 ◽  
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Deep Water ◽  
Wind Waves ◽  
Gas Transfer ◽  
Convective Conditions ◽  
Breaking Wind Waves ◽  
Stable Conditions ◽  
Natural Tendency ◽  
Small Bubbles

Clouds of small bubbles generated by wind waves breaking and producing whitecaps in deep water have been observed below the surface by using an inverted echo sounder. The bubbles are diffused down to several metres below the surface by turbulence against their natural tendency to rise. Measurements have been made at two sites, one in fresh water at Loch Ness and the other in the sea near O ban, northwest Scotland. Sonagraph records show bubble clouds of two distinct types, ‘ columnar clouds’ which appear in unstable or convective conditions w hen the air temperature is less than the surface water temperature, and ‘ billow clouds ’ which appear in stable conditions w hen the air temperature exceeds that of the water. Clouds penetrate deeper as the wind speed increases, and deeper in convective conditions than in stable conditions at the same wind speed. The response to a change in w ind speed occurs in a period of only a few minutes.

scholarly journals The Dynamical Coupling of Wind-Waves and Atmospheric Turbulence: A Review of Theoretical and Phenomenological Models

2021 ◽  
Author(s):  
Alex Ayet ◽  
Bertrand Chapron
Keyword(s):  
Phenomenological Models ◽  
Wind Wave ◽  
Numerical Models ◽  
Wind Waves ◽  
Breaking Waves ◽  
Multiple Time ◽  
Wave Growth ◽  
Breaking Wind Waves ◽  
Turbulent Coherent Structures ◽  
Dynamical Coupling

AbstractWhen wind blows over the ocean, short wind-waves (of wavelength smaller than 10 m) are generated, rapidly reaching an equilibrium with the overlying turbulence (at heights lower than 10 m). Understanding this equilibrium is key to many applications since it determines (i) air–sea fluxes of heat, momentum and gas, essential for numerical models; (ii) energy loss from wind to waves, which regulates how swell is generated and how energy is transferred to the ocean mixed layer and; (iii) the ocean surface roughness, visible from remote sensing measurements. Here we review phenomenological models describing this equilibrium: these models couple a turbulence kinetic energy and wave action budget through several wave-growth processes, including airflow separation events induced by breaking waves. Even though the models aim at reproducing measurements of air–sea fluxes and wave growth, some of the observed variability is still unexplained. Hence, after reviewing several state-of-the-art phenomenological models, we discuss recent numerical experiments in order to provide hints about future improvements. We suggest three main directions, which should be addressed both through dedicated experiments and theory: (i) a better quantification of the variability wind-wave growth and of the role played by the modulation of short and breaking wind-waves by long wind-waves; (ii) an improved understanding of the imprint of wind-waves on turbulent coherent structures and; (iii) a quantification of the interscale interactions for a realistic wind-wave sea, where wind-and-wave coupling processes coexist at multiple time and space scales.

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