Simulations of local and regional scale infrasound propagation in the Arctic

Abstract

High-resolution, three-dimensional reconstructions of the Arctic atmosphere (the Arctic System Reanalysis version 2) are employed as input to wide-angle parabolic equation calculations to simulate infrasound propagation through Arctic weather conditions. The calculations involve horizontal distances out to 200 km (i.e., local and short regional scales), for which interactions with the troposphere and lower stratosphere dominate. The atmospheric phenomena examined include sudden stratospheric warmings (SSWs), strong polar lows, and boundary-layer phenomena such as low-level jets (LLJs), katabatic winds, and surface-based temperature inversions. The SSWs and polar lows are found to be opposites from an acoustic refraction standpoint: the former weaken upward refraction by temperature gradients in the troposphere, thus creating strongly asymmetric wind-dominated refraction, whereas the latter enhance negative temperature gradients in the troposphere, thus leading to prevailing upward refraction conditions. The LLJs and surface-based inversions are found to create particularly strong surface ducting conditions. Horizontal variations in the atmospheric profiles, in response to changes in topography and surface property transitions such as ice boundaries, significantly impact the propagation.