A Detailed Normal-Mode Energetics of the General Circulation of the Atmosphere
Abstract An energetics formulation is here introduced that enables an explicit evaluation for the conversion rates between available potential energy and kinetic energy, the nonlinear interactions of both energy forms, and their generation and dissipation rates, in both the zonal wavenumber and vertical mode domains. The conversion rates between available potential energy and kinetic energy are further decomposed into the contributions by the rotational (Rossby) and divergent (gravity) components of the circulation field. The computed energy terms allow one to formulate a detailed energy cycle describing the flow of energy among the zonal mean and eddy components, and also among the barotropic and baroclinic components. This new energetics formulation is a development of the 3D normal-mode energetics scheme. The new formulation is applied on an assessment of the energetics of winter (December?February) circulation in the 40-yr ECMWF Re-Analysis (ERA-40), the 25-yr Japan Meteorological Agency Reanalysis (JRA-25), and the NCEP?Department of Energy Reanalysis 2 (NCEP-R2) datasets.