Simulation of the Atmospheric Annual Energy Cycle

A two level quasi-geostrophic model for zonally averaged conditions has been integrated for a period of a few years. The model is forced by Newtonian heating and has internal and surface friction. The interaction between the zonal flow and the eddies is simulated through the use of exchange coefficients for the transports of quasi-geostrophic potential vorticity and sensible heat. The results of the integrations show that the model predicts a qualitatively correct annual variation of the zonal winds and the zonal temperature] although the predicted annual cycle has a too large amplitude compared with observations. The times of the maximum amounts of available potential and kinetic energy are well predicted as well as the typical time lag between the two quantities. The same statement holds for the generation of zonal available potential energy and the dissipation of zonal kinetic energy. The energy diagram obtained as an average for 1 yr of integration compares well with the corresponding diagram based on observations. The major weakness of the model (Le.] the large annual variation of most quantities) is probably related to the simplicity of the thermal forcing.