Collective bubble oscillations as a component of surf infrasound.
Plunging surf is a known generator of infrasound, though the mechanisms have not been clearly identified. A model based on collective bubble oscillations created by demise of the initially entrained air pocket is examined. Computed spectra are compared to infrasound data from the island of Kauai during periods of medium, large, and extreme surf. Model results suggest that bubble oscillations generated by plunging waves are plausible generators of infrasound, and that dynamic bubble plume evolution on a temporal scale comparable to the breaking wave period may contribute to the broad spectral lobe of dominant infrasonic energy observed in measured data. Application of an inverse model has potential to characterize breaking wave size distributions, energy, and temporal changes in seafloor morphology based on remotely sensed infrasound.
University of Hawaii, Infrasound Laboratory, 73-4460 Queen Kaahumanu Hwy #119, Kailua-Kona, Hawaii 96740, USA. jpark@isla.hawaii.edu
Joseph
J
Park
Milton
M
Garcés
David
D
Fee
Geno
G
Pawlak
D000162:Acoustics; D007700:Kinetics; D045423:Microbubbles; D008961:Models, Structural; D008962:Models, Theoretical; D009991:Oscillometry; D013016:Sound; D013500:Surface Tension; D013816:Thermodynamics