Effects of the Antarctic elevation on the atmospheric circulation

The orographic effects of Antarctica on the atmospheric circulation are investigated through idealized orographic reduction numerical experiments performed using the NCAR CAM5 model. The investigation shows that, in the absence of the orography over the continent, the troposphere becomes warmer and wetter, the sea level pressure reduces, and the precipitation is enhanced. Furthermore, over the continent, the height of the tropopause increases, the stationary waves become weaker, and the southern polar jet gets more energetic. The radiative budget also gets altered, with more outgoing longwave radiation over the continent, which drives circulation changes beneath. The mean atmospheric circulation is weakened with weakening and shrinking of the Polar cell and widening of the Ferrel cell in the Southern Hemisphere, which decreases the contribution by mean flow towards poleward energy transport. An increase in transient eddy due to an enhancement of baroclinicity over the region supports poleward energy transport and compensates for a higher outgoing longwave radiation over the Antarctic continent. These significant changes observed in idealized Antarctic orographic reduction demonstrate the importance of the present Antarctic orography and ice cover for the Southern Hemisphere. The impact of these changes provides valuable insights on the future role of Antarctic orography on the earth’s climate system from a fundamental point of view.