The turbulent interaction among scale-separated gravity waves and between gravity waves and synoptic-scale flow

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Gravity waves (GWs) play an important role in the dynamics of the atmosphere. Even the highest-resolution weather-forecast models, however, cannot resolve the entire range of gravity waves. The complexity of the resulting parameterization problem is increased by the fact that, where GWs are affected by breaking, wave-turbulence interactions are important. The project intends to address the parameterization of GW emission from synoptic-scale flow, their propagation and breaking by a hierarchical approach. (1) Data from high-resolution direct numerical simulations (DNS) of turbulence from breaking GWs will be used in the development of an implicit sub-grid scale (SGS) turbulence parameterization. These DNS will describe typical paradigms of GW dissipation by focusing on the initial perturbations most effective in leading to wave breaking. (2) A ray-tracing algorithm for the interaction of small-scale GWs with large-scale GWs, an important aspect of GW dynamics, shall be developed and validated against data from large-eddy simulations (LES) of typical cases. (3) Also using LES, the emission of GWs from synoptic-scale flow in a rotating annulus shall be studied. The results shall be compared with those from the laboratory experiment.