Annual and semi-annual changes of atmospheric mass over Antarctica

The annual march of atmospheric pressure at surface is analyzed for fifteen antarctic stations. For a combined series, weighted so that it represents the pressure changes over the entire continent, the first and the second harmonics are shown to be significant. The most pronounced rise, of almost 13 mb, occurs from the end of September to mid-January, concomitant with the partial filling of the southern circumpolar vortex. This rise corresponds to an increase of atmospheric mass over the continent of the order of 2 × 1018 grams. Variations of such magnitude can be important for the meridional mass-exchange in high southern latitudes and for sea level changes of the southern ocean; they also slightly affect the moment of inertia of the earth.