Benchmarking microbarom radiation and propagation model against infrasound recordings: a vespagram-based approach

Type Article
Date 2021-06
Language English
Author(s) Vorobeva EkaterinaORCID1, 2, de Carlo MarineORCID3, 4, Le Pichon Alexis3, Espy Patrick JosephORCID1, Näsholm Sven PeterORCID2, 5
Affiliation(s) 1 : Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
2 : NORSAR, Kjeller, Norway
3 : The French Alternative Energies and Atomic Energy Commission (CEA) – DAM, DIF, 91297 Arpajon, France
4 : Laboratoire d'Océanographie Physique et Spatiale (LOPS), Univ. Brest, CNRS, IRD, Ifremer, IUEM, Brest, France
5 : Department of Informatics, University of Oslo, Oslo, Norway
Source Annales Geophysicae (0992-7689) (Copernicus GmbH), 2021-06 , Vol. 39 , N. 3 , P. 515-531
DOI 10.5194/angeo-39-515-2021
Abstract

This study investigates the use of a vespagram-based approach as a tool for multi-directional comparison between simulated microbarom soundscapes and infrasound data recorded at ground-based array stations. Data recorded at the IS37 station in northern Norway during 2014–2019 have been processed to generate vespagrams (velocity spectral analysis) for five frequency bands between 0.1 and 0.6 Hz. The back azimuth resolution between the vespagram and the microbarom model is harmonized by smoothing the modeled soundscapes along the back azimuth axis with a kernel corresponding to the frequency-dependent array resolution. An estimate of similarity between the output of the microbarom radiation and propagation model and infrasound observations is then generated based on the image-processing approach of the mean square difference. The analysis reveals that vespagrams can monitor seasonal variations in the microbarom azimuthal distribution, amplitude, and frequency, as well as changes during sudden stratospheric warming events. The vespagram-based approach is computationally inexpensive, can uncover microbarom source variability, and has the potential for near-real-time stratospheric diagnostics and atmospheric model assessment.

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