Manabe, S., and A. J. Broccoli, 1984. Ice-age climate and continental ice sheets: some experiments with a general circulation model. Annals of Glaciology, 5, 100-105.
Abstract: The climatic influence of the land ice which existed 18 ka BP is investigated
using a climate model developed at the Geophysical Fluid Dynamics Laboratory
of the National Oceanic and Atmospheric Administration. The model consists
of an atmospheric general circulation model coupled with a static mixed
layer ocean model. Simulated climates are obtained from each of two versions
of the model: one with the land-ice distribution of the present and the
other with that of 18 ka BP.
In the northern hemisphere, the difference in the distribution of sea surface
temperature (SST) between the two experiments resembles the difference between
the SST at 18 ka BP and at present as estimated by CLIMAP Project Members
(1981). In the northern hemisphere a substantial lowering of air temperature
also occurs in winter, with a less pronounced cooling during summer. The
mid-tropospheric flow field is influenced by the Laurentide ice sheet and
features a split jet stream straddling the ice sheet and a long wave trough
along the east coast of North America. In the southern hemisphere of 18
ka BP, the ice sheet has little influence on temperature. An examination
of hemispheric heat balances indicates that this is because only a small
change in interhemispheric heat transport exists, as the in situ radiative
compensation in the northern hemisphere counterbalances the effective reflection
of solar radiation by continental ice sheets.
Hydrologic changes in the model climate are also found, with statistically
significant decreases in soil moisture occurring in a zone located to the
south of the ice sheets in North America and Eurasia. These findings are
consistent with some geological evidence of regionally drier climates from
the last glacial maximum.