Modeling of Acoustic and Gravity Waves Driven by Mesoscale Convective Systems and Their Impacts on the Ionosphere

Mesoscale Convective Systems (MCS) generate upward-propagating acoustic and acoustic-gravity waves (AGWs) that reach high altitudes extending to the upper atmosphere and ionosphere. Ranging from periods of seconds (for acoustic waves) to tens of minutes to hours (for gravity waves), and horizontal wavelengths of several to hundreds of kilometers, the AGW spectrum exhibits both compressional and buoyant dynamics. They impose effects through their momentum and energy fluxes and resulting body forces and flux divergences, their interactions with other waves and flows, and their tendencies towards instability, breaking, and production of turbulence, each leading to nonlinear evolution of their spectra over time. Model simulations of AGWs require consideration of physics within deep, compressible, atmospheres resolving a wide range of scales. Thus, AGWs remain poorly represented in global climatological (general circulation) and weather prediction numerical models, due to the challenges posed both by their physics and diversity of scales.

This presentation highlights our recent results in modeling MCS-driven AGWs and their impacts on the ionosphere over localized regions. We use Global Navigation Satellite System signal-based total electron content (TEC) observations to validate simulations. Employing 3D coupled nonlinear and compressible atmosphere-ionosphere models, MAGIC and GEMINI (Zettergren and Snively, JGR, 2015), we investigate the spatiotemporal evolution of MCS-generated AGW fields, extending beyond prior studies of Heale at al. (GRL, 2019). We examine three recent large convective systems over the continental United States, elucidating common features and differences in their resulting ionospheric dynamics, in comparison to observations.

This research underscores the significance of AGWs in the upper atmosphere and ionosphere, while also hinting at potential applications of measurements from high altitudes to assess MCS characteristics and evolutions. Notably, we emphasize the specific role of MCS in upper atmospheric and ionospheric dynamics, as they create impacts across diverse spatial and temporal scales. The findings also highlight the applicability of contemporary modeling techniques and observational tools for small-scale AGWs, and their nonlinear behaviors and effects in evolving stratified atmospheres. The utility of AGW signal observables, and measurements and simulations thereof, are discussed towards understanding their roles as they impose variability in space weather.

Zettergren, M. D., and Snively, J. B. (2015), Ionospheric response to infrasonic-acoustic waves generated by natural hazard events, J. Geophys. Res. Space Physics, 120, 8002–8024, doi:10.1002/2015JA021116.

Heale, C. J., Snively, J. B., Bhatt, A. N., Hoffmann, L., Stephan, C. C., & Kendall, E. A. (2019). Multilayer observations and modeling of thunderstorm-generated gravity waves over the Midwestern United States. Geophysical Research Letters, 46, 14164–14174. https://doi.org/10.1029/2019GL085934