Features of the zonal mean circulation in the Southern Hemisphere during the last glacial maximum

Abstract

Characteristics of the zonal mean circulation of the Southern Hemisphere during the Last Glacial Maximum (LGM) are investigated. Using a high-resolution global atmospheric climate model set up under Paleoclimate Modeling Intercomparison Project glacial conditions, the output is compared with the output from a control simulation. Accounting for the biases in the model, differences between the control and LGM circulation are ascribed to the climate of the LGM. During the LGM, the mean zonal winds were slightly stronger at midlatitudes and weaker at high latitudes, implying a small equatorward shift of the polar trough in the zonal mean. The amplitude of the wave number 3 pattern of the general circulation was slightly larger, particularly during the austral winter, and there was a slight shift to shorter wavelengths in the planetary waves. Meridional heat transport at midlatitudes was reduced which was mainly the result of an increase in the occurrence and strength of southerly winds. However, meridional heat transport by the transient eddies had increased slightly north of 60°S. Copyright 2007 by the American Geophysical Union.