The key role of topography in altering North Atlantic atmospheric circulation during the last glacial period
Type
Journal articlePeer reviewed
publishedVersion
Date
2011-10-18Author
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Show full item recordAbstract
The Last Glacial Maximum (LGM; 21 000 yr before
present) was a period of low atmospheric greenhouse
gas concentrations, when vast ice sheets covered large parts
of North America and Europe. Paleoclimate reconstructions
and modeling studies suggest that the atmospheric circulation
was substantially altered compared to today, both in
terms of its mean state and its variability. Here we present
a suite of coupled model simulations designed to investigate
both the separate and combined influences of the main LGM
boundary condition changes (greenhouse gases, ice sheet topography
and ice sheet albedo) on the mean state and variability
of the atmospheric circulation as represented by sea
level pressure (SLP) and 200-hPa zonal wind in the North
Atlantic sector. We find that ice sheet topography accounts
for most of the simulated changes during the LGM. Greenhouse
gases and ice sheet albedo affect the SLP gradient in
the North Atlantic, but the overall placement of high and
low pressure centers is controlled by topography. Additional
analysis shows that North Atlantic sea surface temperatures
and sea ice edge position do not substantially influence the
pattern of the climatological-mean SLP field, SLP variability
or the position of the North Atlantic jet in the LGM.
Publisher
Copernicus PublicationsEuropean Geosciences Union
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Copyright Author(s) 2011.