Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C03017, doi:10.1029/2011JC007267.
Description:
Frequency spectra from deep-ocean near-bottom acoustic measurements obtained contemporaneously with wind, wave, and seismic data are described and used to determine the correlations among these data and to discuss possible causal relationships. Microseism energy appears to originate in four distinct regions relative to the hydrophone: wind waves above the sensors contribute microseism energy observed on the ocean floor; a fraction of this local wave energy propagates as seismic waves laterally, and provides a spatially integrated contribution to microseisms observed both in the ocean and on land; waves in storms generate microseism energy in deep water that travels as seismic waves to the sensor; and waves reflected from shorelines provide opposing waves that add to the microseism energy. Correlations of local wind speed with acoustic and seismic spectral time series suggest that the local Longuet-Higgins mechanism is visible in the acoustic spectrum from about 0.4 Hz to 80 Hz. Wind speed and acoustic levels at the hydrophone are poorly correlated below 0.4 Hz, implying that the microseism energy below 0.4 Hz is not typically generated by local winds. Correlation of ocean floor acoustic energy with seismic spectra from Oahu and with wave spectra near Oahu imply that wave reflections from Hawaiian coasts, wave interactions in the deep ocean near Hawaii, and storms far from Hawaii contribute energy to the seismic and acoustic spectra below 0.4 Hz. Wavefield directionality strongly influences the acoustic spectrum at frequencies below about 2 Hz, above which the acoustic levels imply near-isotropic surface wave directionality.
Description:
Funding for the ALOHA
Cabled Observatory was provided by the National Science Foundation
and the State of Hawaii through the School of Ocean and Earth Sciences
and Technology at the University of Hawaii-Manoa (F. Duennebier, PI).
Donations from AT&T and TYCOM and the cooperation of the U.S. Navy
made this project possible. The WHOI-Hawaii Ocean Time series Station
(WHOTS) mooring is maintained by Woods Hole Oceanographic Institution
(PIs R. Weller and A. Plueddemann) with funding from the NOAA
Climate Program Office/Climate Observation Division. NSF grant OCE-
0926766 supported R. Lukas (co-PI) to augment and collaborate on the
maintenance of WHOTS. Lukas was also supported during this analysis
by The National Ocean Partnership Program “Advanced Coupled
Atmosphere-Wave-Ocean Modeling for Improving Tropical Cyclone Prediction
Models” under contract N00014-10-1-0154 to the University of
Rhode Island (I. Ginis, PI).
Description:
2012-09-10
Keywords:
Air-sea interaction
;
Marine acoustics
;
Ocean observatories
;
Ocean waves
;
Wave spectra
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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