Internal gravity waves from atmospheric jets and fronts

International audience[1] For several decades, jets and fronts have been known from observations to be significant sources of internal grav-ity waves in the atmosphere. Motivations to investigate these waves have included their impact on tropospheric convection, their contribution to local mixing and turbu-lence in the upper troposphere, their vertical propagation into the middle atmosphere, and the forcing of its global circulation. While many different studies have consistently highlighted jet exit regions as a favored locus for intense gravity waves, the mechanisms responsible for their emis-sion had long remained elusive: one reason is the complexity of the environment in which the waves appear; another reason is that the waves constitute small deviations from the balanced dynamics of the flow generating them; i.e., they arise beyond our fundamental understanding of jets and fronts based on approximations that filter out grav-ity waves. Over the past two decades, the pressing need for improving parameterizations of nonorographic gravity waves in climate models that include a stratosphere has stim-ulated renewed investigations. The purpose of this review is to present current knowledge and understanding on grav-ity waves near jets and fronts from observations, theory, and modeling, and to discuss challenges for progress in coming years