THE SEASONAL VARIATION OF THE STRENGTH OF THE SOUTHERN CIRCUMPOLAR VORTEX

Abstract

The annual march of the strength of the southern circumpolar vortex is shown to be composed of a simple annual variation (with the maximum occurring in late winter) which dominates in the stratosphere, and a semiannual variation with the maximum at the equinoxes, which is the dominating part in the troposphere. This behavior of the circumpolar vortex is considered to be the consequence of the seasonal variation of radiation conditions and of the different efficiency of meridional turbulent exchange in the troposphere and stratosphere. It is suggested that the semiannual variation of the tropospheric vortex is an essential feature of a planetary circulation. The annual march of pressure with opposite phase values at polar and middle latitudes, can be understood as a consequence of the formation and decay of the great circumpolar vortex.