Three-dimensional topographic effects on infrasound propagation across Ascension Island

نویسندگان

چکیده

SUMMARY Narrowband harmonic infrasound signals within the 1–8 Hz passband, generated by wind turbines on Ascension Island, have been recorded at four microbarometers located distances of between 1.8 and 4.6 km from source along different azimuths. Across one month recordings in October 2010, amplitude ratios show temporal stability but deviate expected for propagation across a flat plane. Using recently developed 3-D parabolic equation method, that can incorporate realistic topography as lower boundary, it is shown these time-independent ratio deviations be, part, explained acoustic interactions with has scale lengths order few hundreds metres. These comprise both 2-D barrier effects reduce sound levels behind high topography, diffractive increase topographic obstacles. For Island case study, amplitudes two paths be successfully modelled using model, indicating dominate path geometries. Amplitude third path, frequency-dependence ratios, are better simulated model captures out-of-plane around prominent hill. The fourth poorly which overpredicts this case. We hypothesize mismatch likely to due simplified description turbine term. This study provides further observational confirmation need considered when interpreting locally propagating infrasound, shows narrowband sources solver incorporating boundary conditions an efficient method simulating interactions.

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ژورنال

عنوان ژورنال: Geophysical Journal International

سال: 2022

ISSN: ['1365-246X', '0956-540X']

DOI: https://doi.org/10.1093/gji/ggac230