| date: | 2013 November 12 (Tue) 15:00-16:00 |
| room: | CPS Conference Room |
| speaker: | Noboru Nakamura (Dept of the Geophysical Sciences, U. Chicago) |
| organizer: | Yoshi-Yuki Hayashi |
| title: | Extending the TEM set for finite-amplitude Rossby wave-mean flow interaction |
| abstract: | Theory of wave-mean flow interaction has been well developed and its mainstay, the Transformed Eulerian Mean formalism, remains popular in the analysis of atmospheric general circulation. Whilst the TEM set describes how and how fast the mean flow is being modified by the waves, it does not address how much the observed mean flow is already modified since its wave equation (the Eliassen-Palm relation) is accurate only up to the second order in wave amplitude. I will describe how this limitation may be lifted for the Rossby wave using Kelvin's circulation theorem, and how the extension allows one to diagnose the partitioning of angular (pseudo)momentum densities between the mean flow and eddy. The extended formalism helps one to (1) describe covariation of the flow and eddy, (2) define a slowly varying, eddy-free reference state and (3) extract the effects of irreversible mixing on the mean flow modification. Relationships to other formalisms such as Generalized Lagrangian Mean will be touched upon. |
| keywords: | general circulation of the atmosphere, wave mean-flow interaction, Rossby wave, TEM (transformed Eulerian mean), GLM (generalized Lagrangian mean), EP (Eliassen and Palm) flux |