The Life Cycle of Gravity Waves Formed by the Release of Inertial Instability Leading to the Production of Clear-Air Turbulence

Atmospheric gravity waves are known to produce turbulence when they dissipate. With turbulence causing 71% of weather-related aviation incidents, it is vitally important to understand the role that gravity waves play in its generation. Given that only 14% of these encounters are attributable to convection, clear-air turbulence (CAT) is their leading cause and is therefore a major risk to air travellers. Numerous dynamical mechanisms are responsible for CAT, and so differentiating between them and disentangling the precise role of gravity waves remains a challenge. In this study, the relationship between gravity waves and CAT is investigated, with the aim of describing the broader life cycle of the waves from generation, within regions of inertial instability, to dissipation, into turbulence. We expand on the work using idealised model simulations by Thompson and Schultz, (2021) to instead consider some real-world examples where inertially unstable regions are associated with gravity wave activity. Weather Research & Forecasting (WRF) model output is used across several case studies to track the propagation of the waves and investigate the causal link found by Thompson and Schultz. From this output, various gravity wave parameters are calculated, and the wave characteristics are compared with the idealised simulations. Finally, our analysis is widened to examine the role of the synoptic regimes which tend to create regions of inertial instability, with the ultimate aim of improving our ability to predict the occurrence of CAT in the future.