The role of the non-axisymmetric Antarctic orography in forcing the observed pattern of variability of the Antarctic climate

The pattern of inter-annual variability in the atmospheric circulation around Antarctica has a maximum over the Amundsen-Bellinghausen Sea (ABS), which is particularly strong during the winter (June, July and August). By using an atmosphere-only general circulation model the causes of this maximum have been investigated. In particular we study the effect of the non-axisymmetric nature of the local surface forcing (sea surface temperatures, sea ice and orography) by imposing axi-symmetric forcing fields at high southern latitudes. The results of these experiments show that the nonaxisymmetric nature of the Antarctic orography is sufficient to explain the variability maximum in the ABS.