The Antarctic Atmospheric Energy Budget. Part I: Climatology and Intraseasonal-to-Interannual Variability

The authors present a new, observationally based estimate of the atmospheric energy budget for the Antarctic polar cap (the region poleward of 70 degrees S). This energy budget is constructed using state-of-the-art reanalysis products from ECMWF [the ECMWF Interim Re-Analysis (ERA-Interim)] and Clouds and the Earth's Radiant Energy System (CERES) top-of-atmosphere (TOA) radiative fluxes for the period 2001-10. The climatological mean Antarctic energy budget is characterized by an approximate balance between the TOA net outgoing radiation and the horizontal convergence of atmospheric energy transport, with the net surface energy flux and atmospheric energy storage generally being small in comparison. Variability in the energy budget on intraseasonal-to-interannual time scales bears a strong signature of the southern annular mode (SAM), with El Nino-Southern Oscillation (ENSO) having a smaller impact. The energy budget framework is shown to be a useful alternative to the SAM for interpreting surface climate variability in the Antarctic region.