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Using anticyclonicity to determine the position of the Southern Hemisphere westerlies: Implications for the LGM
Author(s) -
Wardle Richard
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018792
Subject(s) - westerlies , anticyclone , climatology , southern hemisphere , geology , northern hemisphere , atmospheric circulation , antarctic oscillation , forcing (mathematics) , last glacial maximum , glacial period , climate model , atmospheric sciences , climate change , oceanography , geomorphology
The possible meridional displacement of southern hemisphere westerlies under a different climate regime is examined by studying the characteristics of surface anticyclones. An atmospheric general circulation model is used to simulate the climates of the present day and the Last Glacial Maximum. A vortex‐tracking scheme, applied to the model data, determines the characteristics of southern hemisphere anticyclones. The statistics of anticyclone system density and system strength suggest the glacial epoch had surface westerlies that were displaced poleward over much of the hemisphere during both the summer and winter seasons. The largest displacement occurred in the Australian region during austral winter. The anticyclones also reflect different atmospheric circulations in the past winter climate. These are a weaker tropical circulation and more intense mid‐latitude eddy activity. The simulation results are compared to paleo reconstructions and the consequences of potentially important ocean forcing are highlighted.