A climatology of microbarom detections at the Kerguelen Islands: Unravelling the ambient noise wavefield

Olivier F.C. Den Ouden, Jelle D. Assink, Pieter S.M. Smets, Läslo G. Evers

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The ambient infrasonic noise field is complex due to the interference of spatially distributed infrasound sources. Microbaroms are one of the most dominant omnipresent infrasonic sources within this wavefield. These microbaroms are generated by nonlinear ocean surface wave interactions, and have a characteristic and continuous signature within the infrasound spectrum. Under noisy conditions, microbaroms can mask infrasonic signals of interest, such as infrasound from volcanoes or explosions, which limits detection and identification of such sources. This study performs an infrasonic climatology for infrasound array I23FR, using five years of data between 2015-2020. The array is located on the Kerguelen Islands, within the Southern Ocean, and is part of the International Monitoring System for the verification of the Comprehensive Nuclear-Test-Ban Treaty. The climatology analysis addresses the expected ambient noise levels, propagation paths and potential sources within the vicinity of an infrasound sensor. Time- and frequency-domain beamforming methods have been applied to analyse the infrasonic wavefield from the I23FR observations. A recently introduced method is applied to compute so-called soundscapes, to be compared with beamform results. Although the comparison indicates a disagreement in amplitude, there is a good agreement in directionality and frequency between both.

Original languageEnglish
Pages (from-to)1646-1664
Number of pages19
JournalGeophysical Journal International
Volume229
Issue number3
DOIs
Publication statusPublished - 2022

Keywords

  • Indian Ocean
  • Infrasound
  • Time-series analysis

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