QUASI-STATIONARY WAVES IN THE SOUTHERN-HEMISPHERE .1. OBSERVATIONAL DATA

This Part I presents selected major features of the quasi-stationary ( monthly mean) wave held in the troposphere and stratosphere of the Sou thern Hemisphere. It is confirmed that the quasi-stationary wave with zonal wavenumber 1 (QS-wave 1) is by far the dominant component of the geopotential height field at tropospheric and stratospheric levels. T he amplitude of this wave is largest at about 60 degrees S all year ro und and reaches a maximum during September and October in the upper tr oposphere and stratosphere. Analysis of the Elliasen-Palm flux vector suggests that at high latitudes the quasi-stationary wave field is pri marily forced from lower latitudes, most prominently from the Indian O cean region during June and October. Orographic and thermal forcing fr om Antarctic regions seem to also be important sources of wave activit y in polar and high latitudes, particularly over southern South Americ a and the Atlantic Ocean. The contribution to the quasi-stationary Bow by the transient component of the flow is also analyzed. This analysi s suggests that at high latitudes, the low-frequency transients act to strengthen QS-wave 1, while high-frequency transients weaken it The v alues found for these contributions suggest that the low-frequency com ponent is dominant.