Normal Mode Energetics of the General Circulation during the FGGE Year

Abstract

Abstract Three-dimensional normal mode functions are applied to the analysis of the energetics of the general circulation during the FGGE year. The GFDL FGGE data are used for the computation of both the normal mode energetics and the standard spectral energetics. The normal mode energetics of the global circulation are presented in a barotropic and baroclinic decomposition for the zonal mean and eddy energies for the stationary and transient components of the flow. The energy generated in the zonal mean baroclinic component is first transformed to the eddy baroclinic component through the process of atmospheric baroclinic instability. It is then further transformed to eddy and zonal mean barotropic components by the nonlinear up-scale cascade of kinetic energy. The zonal mean kinetic energy thus maintains its barotropic structure by the activities of baroclinic waves. The time series of energy variables during the FGGE Northern Hemisphere winter clearly indicates a sequence of energy transformations from...