Mesoscale Energy Spectra in Idealized Baroclinic Waves

Michael WaiteUniversity of WaterlooDepartment of Applied MathematicsVarious theories have been proposed for the mesoscale kinetic energy spectrum, which is frequently observed to have an approximately -5/3 power law.  Recent work has converged on the hypothesis of a downscale cascade from larger scales, but the details of this cascade (i.e. the relative importance of inertia-gravity waves, stratified turbulence, etc.) is still unclear.  This talk will examine the development of the mesoscale spectrum in numerical simulations of idealized baroclinic waves.  Experiments are initialized with an unstable mid-latitude jet; moist physics are included but topography, radiation, and surface fluxes are omitted.  Even with such an idealized setup, a rich array of mesoscale motions are found to develop.  The resulting energy spectra have a number of similarities with observations and more comprehensive simulations -- in particular, the spectral slopes of the rotational and divergent kinetic energy are around -3 and -5/3, respectively -- but there are also key differences.  The importance of latent heating in the direct excitation of the mesoscale will be assessed, and implications for the mesoscale cascade theories will be discussed.  This work is in collaboration with Chris Snyder. Thursday, 8 November 2012, 3:30 PMRefreshments 3:15 PMNCAR-Foothills Laboratory3450 Mitchell LaneBldg 2, Large Auditorium Room 1022                                   

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Thursday, November 8, 2012 - 3:30pm