Group seminar on 20. June, 14:15 CET
Mixed Rossby-gravity wave generation by wave-mean flow interactions in the atmosphere
The mixed Rossby-gravity (MRG) waves contribute significantly to tropical variability, which provides motivation to examine how these waves are excited in the atmosphere. We propose wave-mean flow interactions as a generation mechanism for MRG waves and show that this process is capable of explaining the scale selection of MRG waves in the troposphere and also in the stratosphere. This mechanism is detected by idealized numerical simulations with the TIGAR model, which has the MRG waves as prognostic quantities. This enables to quantify spectral tendencies associated with the growth of the MRG waves. The results highlight the role of wave-mean flow interactions in comparison to generation mechanisms driven by external forcing and wave-wave interactions. This talk will give a comprehensive overview of the MRG wave excitation focusing mostly on wave-mean flow interactions as well as barotropic instability.