Frequency-dependent noise sources in the North Atlantic Ocean

Type Article
Date 2013-12
Language English
Author(s) Sergeant Amandine1, Stutzmann Eleonore1, Maggi Alessia2, Schimmel Martin3, Ardhuin FabriceORCID4, Obrebski Mathias4
Affiliation(s) 1 : Univ Paris Diderot, CNRS, Inst Phys Globe Paris, Sorbonne Paris Cite, F-75005 Paris, France.
2 : Univ Strasbourg EOST, CNRS, Inst Phys Globe Strasbourg, Strasbourg, France.
3 : ICTJA CSIC, Inst Earth Sci Jaume Almera, Barcelona, Spain.
4 : IFREMER, Lab Oceanog Spatiale, Plouzane, France.
Source Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2013-12 , Vol. 14 , N. 12 , P. 5341-5353
DOI 10.1002/2013GC004905
WOS© Times Cited 18
Keyword(s) noise sources, secondary microseism, North Atlantic Ocean, polarization
Abstract [1] Secondary microseisms are the most energetic waves in the noise spectra between 3 and 10 s. They are generated by ocean wave interactions and are predominantly Rayleigh waves. We study the associated noise sources in the North Atlantic Ocean by coupling noise polarization analysis and source mapping using an ocean wave model that takes into account coastal reflections. From the Rayleigh wave polarization analysis, we retrieve the back azimuth to the noise sources in the time-frequency domain. Noise source modeling enables us to locate the associated generation areas at different times and frequencies. We analyze the distribution of secondary microseism sources in the North Atlantic Ocean using 20 broadband stations located in the Arctic and around the ocean. To model the noise sources we adjust empirically the ocean wave coastal reflection coefficient as a function of frequency. We find that coastal reflections must be taken into account for accurately modeling 7–10 s noise sources. These reflections can be neglected in the noise modeling for periods shorter than 7 s. We find a strong variability of back azimuths and source locations as a function of frequency. This variability is largely related to the local bathymetry. One direct cause of the time-dependent and frequency-dependent noise sources is the presence of sea-ice that affects the amplitude and polarization of microseisms at stations in the Arctic only at periods shorter than 4 s.
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