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The depression of tropical snow lines at the Last Glacial Maximum: what can we learn from climate and model experiments?

Kageyama, M., Harrison, S. P. and Abe-Ouchi, A. (2005) The depression of tropical snow lines at the Last Glacial Maximum: what can we learn from climate and model experiments? Quaternary International, 138-139. pp. 202-219. ISSN 1040-6182

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To link to this item DOI: 10.1016/j.quaint.2005.02.013

Abstract/Summary

Analyses of simulations of the last glacial maximum (LGM) made with 17 atmospheric general circulation models (AGCMs) participating in the Paleoclimate Modelling Intercomparison Project, and a high-resolution (T106) version of one of the models (CCSR1), show that changes in the elevation of tropical snowlines (as estimated by the depression of the maximum altitude of the 0 °C isotherm) are primarily controlled by changes in sea-surface temperatures (SSTs). The correlation between the two variables, averaged for the tropics as a whole, is 95%, and remains >80% even at a regional scale. The reduction of tropical SSTs at the LGM results in a drier atmosphere and hence steeper lapse rates. Changes in atmospheric circulation patterns, particularly the weakening of the Asian monsoon system and related atmospheric humidity changes, amplify the reduction in snowline elevation in the northern tropics. Colder conditions over the tropical oceans combined with a weakened Asian monsoon could produce snowline lowering of up to 1000 m in certain regions, comparable to the changes shown by observations. Nevertheless, such large changes are not typical of all regions of the tropics. Analysis of the higher resolution CCSR1 simulation shows that differences between the free atmospheric and along-slope lapse rate can be large, and may provide an additional factor to explain regional variations in observed snowline changes.

Item Type:Article
Refereed:Yes
Divisions:Interdisciplinary centres and themes > Walker Institute
Faculty of Science > School of Archaeology, Geography and Environmental Science > Earth Systems Science
Faculty of Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Interdisciplinary centres and themes > Centre for Past Climate Change
ID Code:35932
Publisher:Elsevier

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