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Figure 1. Simulated January and July upper-level (500mb) winds. Wind directions
are shown by arrows, and velocity by shading. The outline of the region covered by ice in
the model is also shown. Polar stereographic projection, principal meridian 100 W.(Fig1.gif, 177KB / Fig1.pdf,
528KB)
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Figure 2. Simulated January and July sea-level pressure and surface winds.
Surface wind directions are shown by arrows, sea-level pressure by shading.(Fig2.gif, 173KB / Fig2.pdf,
535KB)
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Figure 3. Simulated January and July near-surface air temperature (C).(Fig3.gif, 100KB / Fig3.pdf,
343KB)
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Figure 4. Simulated January and July monthly total precipitation (mm).(Fig4.gif, 107Kb / Fig4.pdf,
342KB)
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Figure 5. Simulated January and July near-surface air temperature (C), generated
by interpolating anomalies (paleoclimatic experiment minus present control) onto a 25km
gridded data set of the present values of these variables. The "Present" map
panels are those observed present values. Albers projection, standard parallels at 66.66 N
and 33.33 N, principal meridian 120 W. Paleogeography from Dyke and Prest (1987)
and Peltier (1994).(Fig5.gif, 126KB / Fig5.pdf, 2343KB)
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Figure 6. As in Fig. 5, only for January and July monthly total precipitation.(Fig6.gif, 128KB / Fig6.pdf,
2291KB)
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Figure 7. Observed distributions of Picea spp. (all North American species
of spruce), Pseudotsuga menziesii (Douglas-fir), and Artemisia tridentata
(sagebrush), simulated probabilities of occurrence obtained using the response surfaces
for these taxa and the observed present climate, and illustrations of the response
surfaces for each.(Fig7.gif, 105KB / Fig7.pdf, 1035KB)
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Figure 8. Dimension of the climate space (i.e. number of climate variables) used
in the evaluation of the response surfaces at each grid point and time.(Fig8.gif, 59KB / Fig8.pdf,
1111KB)
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Figure 9. Observed (top) and simulated (bottom) incidence and abundance of Picea
spp. (Fig9.gif, 123KB / Fig9.pdf, 1564KB)
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Figure 10. As in Fig. 9, only for Pseudotsuga menziesii and Artemisia
tridentata.(Fig10.gif, 118KB / Fig10.pdf, 2975KB)
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Figure 11. Proportions of sites with paleoecological data from the western United
States correctly predicted present or absent for each taxon at each time (top), observed
proportion of sites with each taxon present (middle), and predicted proportion of sites
with each taxon present (bottom).(Fig11.gif,
42KB / Fig11.pdf, 8KB)
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Figure 12. Anomalies (paleoclimatic experiment minus modern control simulations)
of energy- and moisture-balance components (Table 2) for grid points representing the
southeastern United States (Table 3). The similarity across experiments in the seasonal
profiles of the anomalies of net SW radiation, latent and sensible heating rates, soil
moisture and P-E reveal the influence of the surface energy- and water-balance processes
in near-surface air temperatures that in summer were not significantly cooler than
present.
(Fig12a.gif, 43KB / Fig12a.pdf, 33KB / Fig12b.gif, 34KB / Fig12b.pdf, 19KB)
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Figure 13. As in Fig. 12, for grid points representing eastern Beringia. In
contrast to the southeastern U.S. where surface energy- and water-balance components acted
to increase near-surface temperatures relative to airmass temperatures (Fig. 12), the
relatively high near-surface air temperatures after 16 ka in eastern Beringia seem
related to increased LW radiation gain (or decreased loss) from warm airmasses advected
into the region.
(Fig13a.gif, 40KB / Fig13a.pdf, 31KB / Fig13b.gif, 34KB / Fig13b.pdf, 21KB)
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Figure 14. As in Fig. 12, for grid points representing western Beringia. The
similarity across the 16 ka to 6 ka experiments in the seasonal profiles of the anomalies
of near-surface and 850mb temperatures together with the small anomalies of sensible
heating rate suggest that as in eastern Beringia, the relatively warm conditions in summer
in western Beringia are related to the advection of warm airmasses into the region.(Fig14a.gif, 38KB / Fig14a.pdf,
30KB / Fig14b.gif, 30KB / Fig14b.pdf,
17KB)
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Figure 15. As in Fig. 12, for grid points representing the Pacific Northwest. In
this region the similarity across simulations between the seasonal profiles of
near-surface and 850mb temperatures suggest that the near-surface temperature anomalies
are determined mainly by the advection of airmasses into the region, although the positive
sensible heating anomalies in summer (apparently related to negative surface wetness
anomalies) also suggest some modification of the advected airmass temperatures by surface
energy- and water-balance processes.
(Fig15a.gif, 40KB / Fig15a.pdf, 32KB / Fig15b.gif, 33KB / Fig15b.pdf, 20KB)
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Figure 16. As in Fig. 12, for grid points representing the southwestern United
States. This region displays the greatest similarity across simulations between the
seasonal profiles of near-surface and 850mb temperatures, which suggests little
modification of the advected airmass temperatures by surface energy- and water-balance
processes.(Fig16a.gif, 37KB / Fig16a.pdf, 31KB / Fig16b.gif, 30KB / Fig16b.pdf, 17KB)
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Figure 17. As in Fig. 12, for grid points representing Mexico. The
greater-than-present anomalies in summer at 11 ka and 6 ka in rising motions, cloudiness,
precipitation, and latent heating rate reflect the development of a stronger summer
monsoon at those times.(Fig17a.gif,
38KB / Fig17a.pdf, 29KB / Fig17b.gif,
31KB / Fig17b.pdf, 17KB)
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