On the maintenance of the kinetic energy of mean zonal flow in the southern hemisphere

Wind data reported at the eight pressure levels (850, 700, 500, 400, 300, 200, 100 and 50 mb) for 121 Southern Hemisphere plus 22 Northern Hemisphere equatorial stations during the calendar year 1958 has enabled us to study the rate of generation of the kinetic energy of the mean zonal flow. The results indicate that the kinetic energy of the mean zonal motion is maintained against frictional dissipation to a large extent through a conversion of transient eddy kinetic energy through the action of the horizontal wind. The generation of zonal kinetic energy by mean meridional motion through the action of the coriolis force cannot be measured well enough, but is probably small as in the Northern Hemisphere. The standing eddy transformation integral appears to be unimportant—a result which is not true for the Northern Hemisphere. If the conversion of the kinetic energy of the transient eddies into the kinetic energy of the mean zonal flow were to cease, the atmosphere of the Southern Hemisphere would be in solid rotation in about 2 1/2 weeks. This assumes a continuation of a normal rate of dissipation during this period.