A Note on the Kinetic Energy Balance of the Zonal Wind Systems

Broadly speaking, there are two processes that may produce the needed transport of angular momentum from the zones of surface easterlies to those of surface westerlies. One is a largescale mean convective process, with axending motions in lower latitudes and descending motions in higher latitudes. The other is the largexale eddy motions. Although some types of mean meridional circulations might be able to account for the necessary transport, the existence of such circulations is hard to establish observationally. On the other hand, the investigations conducted at the Massachusetts Institute of Technology and at the University of California have demonstrated that the eddy process not only produces enough angular momentum transfer but also produces sufficient transfer of energy to maintain the atmosphere in radiational equilibrium. This suggests that the general circulation is maintained mainly by the large-scale eddy process.