The impact of gravity wave parameterizations on the upper atmosphere ICON model and infrasound propagation.

Infrasound signals are generated by various anthropogenic and natural sources, and are one of the technologies used in monitoring compliance with the Comprehensive Nuclear-Test Ban Treaty (CTBT). It is, therefore, of interest to study and better understand the impacts of atmospheric parameters, notably gravity waves (GW), on infrasound propagation. Middle-atmosphere dynamics, up to the lower thermosphere, must be simulated to account for the different acoustic waveguides that allow the long-range propagation and infrasound detections by the CTBT’s International Monitoring System.

 

Since infrasound propagates up to the lower thermosphere, an upper atmospheric model like the upper-atmosphere extension of the ICON model (UA-ICON) is necessary to properly understand and predict infrasound propagation. Toward this goal, we will present studies of UA-ICON using two different GW parameterizations: the operational one also used for the operational ICON forecasts issued by DWD, and a 3D gravity wave parameterization scheme (MS-GWaM) that includes improved GW propagation. We also propose a method to derive stochastic predictions of realistic GW perturbation profiles using MS-GWaM. These results are compared to lidar observations, showing the importance of correctly tuned GW parameterizations on temperature profiles, from tropical to high latitudes. In addition, we will present case studies of infrasound propagation to highlight the importance of mesospheric wind and temperature, as well as GWs, on infrasound propagation and source localization. Notably, infrasound allows us to investigate equatorial latitudes where lidar measurements are missing.