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Michael S. Pritchard, Andrew B. G. Bush, and Shawn J. Marshall

-yr control simulation of modern climate. The regional distribution of El Niño temperature and precipitation anomalies in the AOGCM is largely in agreement with observations from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis ( Fig. 2 ; Kalnay et al. 1996 ) although the magnitude of the thermal response is underestimated, most likely because of diffusive effects associated with the relatively coarse atmospheric model resolution

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Alex S. Gardner, Martin J. Sharp, Roy M. Koerner, Claude Labine, Sarah Boon, Shawn J. Marshall, David O. Burgess, and David Lewis

on-glacier measurement increases. This suggests that NARR, and likely other regional/global climate models, does a better job at simulating higher-elevation temperatures (which are closer to free-air values) than temperatures at lower elevations [which are more strongly influenced by complex local effects, e.g., topography, katabatic winds, higher frequency of surface melt (stronger sensible heat flux), and increased influence from low-lying cloud]. Our approach to downscaling involves two steps

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Shawn J. Marshall and Martin J. Sharp

al. 1996 ). However, the meteorological data demands and the spatial variability of the governing processes make it difficult to apply a rigorous energy balance model in ice sheet–climate modeling. This is also true for paleoclimate studies and for regional-scale modeling studies, in which climatic fields need to be interpolated or downscaled to the region of interest (e.g., Radić and Hock 2006 ). In these situations, degree-day or “temperature index” models are commonly used to parameterize

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J. Paul Spence, Michael Eby, and Andrew J. Weaver

IPCC TAR reported that a lack of experiments exploring the impacts of resolution restricts the ability to draw firm conclusions. We address this need by investigating AMOC variability in a series of global models with horizontal resolutions increasing into the ocean eddy-permitting range. Of the few studies that have systematically examined the effects of increasing model resolution, none evaluated differences in the response to deep water formation perturbations. Earlier research focused on ocean

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Garry K. C. Clarke, Etienne Berthier, Christian G. Schoof, and Alexander H. Jarosch

: Application of inventory data for estimating characteristics of and regional climate-change effects on mountain glaciers: A pilot study with the European Alps. Ann. Glaciol. , 21 , 206 – 212 . Hewitson , B. C. , and R. G. Crane , 2002 : Self-organizing maps: Application to synoptic climatology. Climate Res. , 22 , 13 – 26 . Hsieh , W. W. , 2001 : Nonlinear canonical correlation analysis of the tropical Pacific climate variability using a neural network approach. J. Climate , 14 , 2528

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Stephen D. Griffiths and W. Richard Peltier

Oceans. In our tidal modeling, no account is taken of floating ice shelves such as those that exist around much of present-day Antarctica. These imply a reduction in the ocean depth and an additional drag on the flow due to a turbulent boundary layer at the water–ice interface. The omission of these effects does not appear to degrade the present-day global solutions, perhaps because the extent of the ice shelves is small. At LGM, the extent of ice shelves was presumably much larger than at present

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Garry K. C. Clarke, Andrew B. G. Bush, and John W. M. Bush

Hudson Strait (B in Fig. 2b ), and the flood pulse from Lake Agassiz (C in Fig. 2c ). The forcing A + B + C represents the combined effects of rerouting and the release of stored water in the lake. The B + C forcing (no preflood flow to the Gulf of St. Lawrence) is appropriate to the case where the discharge to the St. Lawrence is highly turbid and possibly hyperpycnal, an idea that is explored in the next section. The A + B + C and B + C forcings can be viewed as end members of a continuum of

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Marc d’Orgeville and W. Richard Peltier

barotropic transports between the two control simulations are primarily due to the effects of the thermohaline circulation and of the bottom velocity, an effect caused by the variable bathymetry. To summarize, the two major differences in mean states of the North Atlantic basin between the two control simulations appear to be in the barotropic circulation (because of the interaction with the bottom bathymetry) and in the sea ice coverage (because of a warmer climate). In contrast, 1870-control 2 appears

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