Infrasound stratospheric guiding and propagation simulations investigated using high-resolution global models resolving gravity waves

The infrasound station network of the International Monitoring System (IMS) is one of the verification technology for the Comprehensive Nuclear-Test ban Treaty (CTBT). The detection capability of this network is modulated by middle atmospheric winds and temperatures, among other factors. Infrasound guiding is indeed affected by the seasonal changes in stratospheric winds driven by thermal wind balance, with westerly winds in the winter season and easterly winds in the summer season of both hemispheres. Gravity waves (GW) are critical to this respect as they alter the propagation path of the waves in the middle atmospheric waveguide. For instance, GW create regional wave guides, affect turning height of the rays in the middle atmosphere, leading to shrinking of the geometrical shadow zone. Therefore, it is important to investigate ways of accounting for these perturbations in the atmospheric fields prescribed in propagation models. Working with models explicitly resolving a part of the GW spectrum is a possible approach, which deserves to be considered given increasing computing means made available by HPC facilities. We use modelled atmospheric fields obtained in the framework of the Dynamics of the Atmospheric General Circulation Modeled on Nonhydrostatic Domains (DYAMOND) project. This international project, initiated by the Max Planck Institute for Meteorology (MPIM) and the University of Tokyo, describes a framework for the intercomparison of high-resolution global atmospheric models. It mainly focuses on tropospheric weather, but some models were run with a high enough top so that GW are resolved up to the stratosphere (~45 km). We use the Icosahedral Non-hydrostatic (ICON) model outputs of DYAMOND. ICON is a non-hydrostatic numerical weather prediction and research model jointly developed by the MPIM and by the German Meteorological Service (DWD). First, we use Rayleigh lidar observations to assess the modelled fields at Observatoire de Haute Provence (OHP, France), and we investigate GW properties across the IMS. Then we discuss how critical GW are with respect to large scale effects at OHP and IMS stations. Effective wind speed ratio considerations and infrasound propagation simulations are used in this endeavor.