Global Microbarom Patterns: a First Confirmation of the Theory for Source and Propagation

Type Article
Date 2021-02
Language English
Author(s) de Carlo M.ORCID1, 2, Hupe P.ORCID3, Le Pichon A.ORCID1, Ceranna L.ORCID3, Ardhuin FabriceORCID4
Affiliation(s) 1 : CEA, DAMDIFF‐91297 Arpajon, France
2 : Université de Bretagne Occidentale, Brest, France
3 : BGR, B4.3 Hannover, Germany
4 : University of Brest, CNRS, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM, Brest, France
Source Geophysical Research Letters (0094-8276) (American Geophysical Union (AGU)), 2021-02 , Vol. 48 , N. 3 , P. e2020GL090163 (10p.)
DOI 10.1029/2020GL090163
WOS© Times Cited 15
Keyword(s) ambient noise, infrasound, microbaroms, wave modeling

Microbarom signals are generated by wind‐waves at the ocean surface and propagate all around the globe through the stratosphere and ionosphere. Microbaroms dominate the coherent infrasound ambient noise measured worldwide, with a peak around 0.2 Hz. Monitoring these signals allows characterizing the source activity and probing the properties of their propagation medium, the middle atmosphere. Here we show the first quantitative validation of global microbarom modeling based on ocean wave models, a new source model and atmospheric attenuation. For evaluating these parameters’ impact, we compare the modeling results with a global reference database of microbaroms detected by the infrasound International Monitoring System over seven years. This study demonstrates that the new source model improves the prediction rate of observations by around 20 percent points against previous models. The performance is enhanced when the new model is combined with a wind‐dependent attenuation and an ocean wave model that includes coastal reflection.

Plain Language Summary

Microbaroms are atmospheric ambient noise below the human hearing threshold. They are generated by ocean waves and can be detected by infrasound sensors worldwide. A better understanding is important because microbaroms could hide signals of interest in the context of the Comprehensive Nuclear‐Test‐Ban Treaty, established to unveil clandestine nuclear explosions worldwide. Furthermore, as microbaroms propagate over long‐ranges through the middle atmosphere, a better knowledge of the received signals provides new insights of middle atmosphere dynamics features that are unresolved in global circulation models. In this study, we use a historical database of microbarom detections to evaluate state‐of‐the‐art models and propose a methodology to simulate microbaroms worldwide.

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