Microbarom radiation and propagation model assessment using infrasound recordings: a vespagram-based approach

• Main Authors: Vorobeva, Ekaterina, Carlo, Marine, Pichon, Alexis, Espy, Patrick Joseph, Näsholm, Sven Peter
• Format: Text
• Language: English
• Published: 2020
• Subjects: Norway; Northern Norway
• Online Access: https://doi.org/10.5194/angeo-2020-78; https://angeo.copernicus.org/preprints/angeo-2020-78/

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 vespagrams and a microbarom model is harmonized by smoothing the modelled soundscapes along the back-azimuth axis with a kernel corresponding to the frequency-dependent array resolution. An estimate of similarity between the output of a microbarom radiation and propagation model and infrasound observations is then generated based on the image processing approach of mean-square difference. The analysis revealed that vespagrams can monitor seasonal variations in the microbarom azimuth distribution, amplitude, and frequency, as well as changes during sudden stratospheric warming. The vespagram-based approach is computationally inexpensive, can uncover microbarom source variability, and has potential for near-real-time stratospheric diagnostics and atmospheric model assessment.