摘要：Climates of the past, such as the Last Glacial Maximum (LGM), give a useful insight into the response of atmosphere and ocean processes to various forcings that were different to the present day. The use of General Circulation Models aids in understanding past climates in combination with the available proxy data. In this study, a selection of models from the Paleoclimate Modelling Intercomparison Project was used to assess the changes in Southern Hemisphere atmospheric variability on seasonal to interannual time-scales. The evidence from two of the models suggests a seasonal deepening of the circumpolar trough (CPT) during the LGM relative to present day, with enhanced tropospheric westerlies in all seasons. The third model suggested there was a weakening of the CPT in all seasons except austral spring, where a strengthening was simulated. Finally, the work considers how the Southern Annular Mode may have been different in the LGM for the three models under consideration.
关键词：Southern Hemisphere; Last Glacial Maximum; semiannual oscillation; southern annular mode; general circulation model; PMIP2; circumpolar trough
