Internal Oscillations of Tropical Mesoscale Convective Disturbances

In real-world observations, long-lived tropical mesoscale convective disturbances (MCDs) often exhibit quasi-periodic variations. Previous studies suggested that these variations are mainly induced by external forcings. However, some studies showed evidence that tropical MCDs can display quasi-periodic behavior even without external forcings. In this study, a suite of idealized convection-permitting simulations is used to examine the evolution of a mesoscale atmospheric column after an initial pulse of heating. It is demonstrated that the heated column not only radiates inertia-gravity waves that perturb its environment, but itself continues to oscillate with consequences for subsequent local convection. By comparing simulations with linear wave theory, it is suggested that this oscillation is an inertia-gravity oscillation. This study indicates that convectively coupled internal oscillations may constitute a fundamental component of the life cycle of observed long-lived tropical MCDs.