Application of propagation modeling to verify and discriminate ground-truth infrasound signals at regional distances

Kurzfassung

An infrasound field campaign was performed in 2011/2012 utilizing six single infrasound sensors along the great circle path between a known infrasound ground-truth source (ARIANE 5 engine test facility, Lampoldshausen, Germany) and a nearby receiver (German infrasound array I26DE, Bavarian Forest) covering a distance of about 320km in total. The recordings gathered provide new insights in the infrasonic wave propagation at regional distances and, in particular, through the near-source shadow zone by comparing measured signals with modeling results. Infrasound propagation modeling utilizing ray-tracing and parabolic equation approaches is performed to explain detections and non-detections at certain ranges from the ground-truth source. Modeling results show a significant influence of small-scale atmospheric variations (of e.g. wind and sound speed) on the propagation pattern, resulting in varying tropospheric and stratospheric ducting behavior. An extensive set of gravity wave profiles was tested to investigate the influences of atmospheric dynamics on the infrasound wave field and improve the modeling results. The modeling is also applied to complementary detections obtained during the field campaign; namely one case associated with two potential, contemporaneous and closely spaced infrasound sources, is presented in detail. Propagation modeling is used to resolve the source ambiguity between a ground-based and a higher altitude source and give a strong preference with respect to the observed infrasonic signatures.