On the position of southern hemisphere westerlies at the Last Glacial Maximum: an outline of AGCM simulation results and evaluation of their implications

The paper evaluates the claim of a poleward displacement of the southern he misphere mid-latitude westerly circulation at the Last Glacial Maximum (LGM ). The claim was initially based on the interpretation of the Late Quaterna ry paleoenvironmental records of southern South America and drew on concept ual paleo-circulation reconstructions and the results of early AGCM simulat ions. A guide to likely LGM changes in the position of the southern hemisph ere westerlies can in principle be obtained through a modelling of associat ed storm tracks. A detailed analysis of the position of the southern hemisp here storm tracks at the LGM was undertaken using the UGAMP GCM. The result s of the experiment suggest that a general poleward displacement of the zon al maximum of the southern hemisphere westerlies occurred at the LGM. But t his is a generalization and in detail the changes in the westerly circulati on are more far-ranging with significant regional differences. (C) 2000 Els evier Science Ltd. All rights reserved.