On the Genesis of Divergence and Gravity Wave Emission from Oscillating Barotropic Vortices in Rotating Fluids

Internal gravity waves are ubiquitous in the atmosphere. Our understanding of gravity wave emission from atmospheric jet-front systems, such as the baroclinic vortices, has considerably improved over the past decade. Interestingly, even unstable barotropic jets are known to emit gravity waves. However, the wave generation mechanism in barotropic vortices is thought to be different than in baroclinic vortices. Yet, our current understanding of the wave generation mechanism fails to draw a clear distinction between the emission mechanisms in barotropic and baroclinic vortices; indicating that a deeper understanding of the wave generation is required than which is currently known. The present study focuses on gaining a better understanding of gravity wave generation mechanism from unstable barotropic jets. A more detailed study of the wave emission mechanism is performed compared to the earlier studies. New details about the wave forcing mechanism from unstable barotropic jets are identified, which provides a much clear picture of the wave emission mechanism from barotropic jets. The role of planetary vorticity in inhibiting gravity wave emission and its representation in the Ford-Lighthill formulation is elucidated. Gravity wave emission associated with vortex merging is also investigated. This study also provides important insight on the source and significance of divergence in fluid motions