Infrasound Propagation Calculation Techniques Using Synoptic and Mesoscale Atmospheric Specifications

Numerical modeling of infrasound propagation is necessary to support accurate infrasound source location and phase identification. Predicting the details of infrasound propagation relies both on propagation models that capture the fundamental physical processes and on characterization of the propagation medium, namely the global atmosphere from the ground to altitudes above 100 km. The accuracy of propagation modeling depends in part on the fidelity of the atmospheric characterization. The analysis tool kit InfraMAP (Infrasound Modeling of Atmospheric Propagation) integrates infrasound propagation models and environmental representations, including near-real-time atmospheric updates, such as the output from numerical weather prediction models that supplement the baseline climatological characterization of temperature, wind and air composition. These capabilities allow infrasound researchers to investigate critical propagation phenomena, conduct sensitivity studies, and compare results of numerical modeling with observed signals. Recent efforts aim to evaluate and quantify the propagation improvements attainable using global and synoptic specifications that characterize the relevant atmospheric physics more fully than climatological models. Global synoptic models provide specifications that are well-suited for use in long-range propagation predictions. Further investigation of infrasound propagation phenomenology on a regional basis and development of suitable tools for studying regional events are necessary. Thus we investigate combining accurate, high-resolution regional atmospheric specifications with infrasound propagation modeling codes. Mesoscale models, which focus on the meteorology of a specific region, can better account for and resolve important meteorological phenomena relevant to regional and local infrasound propagation. By investigating realistic spatial and temporal atmospheric models at a range of resolutions, we seek insight into the appropriate spatial and temporal scales that are necessary for achieving improved infrasound predictions at the relevant frequencies. Approaches are being developed to assess performance of candidate techniques for incorporating mesoscale atmospheric models and terrain specifications with propagation models and to evaluate the benefits. Evaluation of propagation model performance using synoptic and mesoscale atmospheric specifications utilizes observed infrasound events with known ground truth. 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies