Group seminar on 29. November, 14:15 CET

A mixed Rossby-gravity wave climatology based on ERA5 re-analyses and three-dimensional normal mode decomposition

Dr. Frank Lunkeit

A mixed Rossby-gravity wave (MRGW) climatology based on 40 years ERA5 reanalyses data is presented. A three-dimensional normal mode decomposition (MODES) is utilized to identify MRGW activity. Properties of MRGW variability are shown in grid point space and in spectral space provided by the decomposition. Substantial differences are found between MRGW activity in the upper troposphere and the upper stratosphere. For intramonthly variability, the contribution of smaller zonal wavenumbers (k=1-3) is larger in the upper stratosphere than in the upper troposphere where zonal wavenumbers around k=6 dominate. Results from wavenumber-frequency diagnostics applied to the MODES filtered MRGWs suggest a great importance of non-linear processes for both levels.