Energetics of Easterly Waves

Abstract

The energetics of a numerically simulated easterly wave is studied. A quasi-geostrophic model is used. The easterly wave is generated by specifying a diabatic heating wave which represents the effects of deep cumulus convection. The various components of the kinetic as well as the available potential energy budgets are computed from the simulated velocity and temperature fields. The results of this study indicate that the observed velocity and thermal structures of the active easterly wave are mutually consistent with the concept that diabatic heating in the upper troposphere is the ultimate source of energy for all levels in the atmosphere. This diabatic heating generates available potential energy which is converted to kinetic energy in the same regions where heating occurs. The kinetic energy, which is generated in the upper troposphere, is exported by the mechanism of wave potential energy flux to other levels. This export tends to balance the kinetic energy depletion associated with frictional dissipation and indirect circulations in the lower troposphere.