A recent theory on the spontaneous emission of gravity waves (GWs) during the evolution of a near balance flow (i.e. spontaneous adjustment), predicts the GW field based on potential vorticity (PV) anomalies in vertically sheared flows. Based on this theory, we adapt a recently developed stochastic parameterization of gravity waves to represent the GWs produced by mid-latitude fronts and jets. With relatively little modification to the theory, we show that the parameterization produces a realistic GW drag and momentum-flux intermittency, and that it performs at least as well as classical schemes that have been thoroughly tuned during the past 20 years. The impacts on the climate are addressed with the LMDz General Circulation Model, with a particular emphasis on the annual cycle in the middle atmosphere. We find that when GW sources are included the GW momentum flux emitted presents a pronounced annual cycle. Although the GW filtering by the background winds strongly determines the annual cycle of the GW drag in the middle atmosphere, we will show that a source-related intensified annual cycle in the drag modulates the meridional circulation, especially in the Northern Hemisphere. We also address the significance of including the GWs sources on the middle atmosphere response to a changing climate. Preliminary results show that when GW sources are included, the mean meridional circulation response to climate change is slightly stronger than without GW sources.

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*email: acamara@ucar.edu
*Preference: Poster