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

1. Introduction Although high-frequency climate variability on the annual to subannual scale is reasonably well understood, there is an ongoing effort to account for observed low-frequency climate variability on interdecadal to millennial scales. A recent approach that has helped to address this problem is the incorporation of higher-frequency external forcing mechanisms into models of lower-frequency processes. Several such studies have provided useful insight into the evolution of slow modes

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

above it (H. Huppert 2007, personal communication); therefore no upper-ocean freshening would be possible in such a circumstance. This uncertainty clouds discussion of whether, during the flood phase, the outflow through Hudson Strait was also densely sediment laden. If this were the case, then the B forcing model could provide the best representation of the near-surface freshwater forcing of the Labrador Sea. We have simulated this situation as well but the results are not sufficiently different

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Guido Vettoretti, Marc d’Orgeville, William R. Peltier, and Marek Stastna

modern AOGCMs ( Guilyardi 2006 ) and is likely due to a number of problems (e.g., resolution, cloud and convective parameterizations, etc.). One recent study notes a marked improvement in tropical dynamics when an improved cumulus convective parameterization is added to the model used in this study ( Wu et al. 2007 ). A time series of the 1-Sv Niño-3.4 SST index ( Fig. 9e ) reveals large-amplitude El Niño and La Niña events during and after the 100-yr period during which the freshwater forcing is

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Shawn J. Marshall and Martin J. Sharp

be a consequence of local continental and marine influences at these marginal sites. The western margins experience warm air advection from the adjacent land, whereas fog and cloud cover on the east coast reduce summer temperatures and lower PDD relative to the model. The climate forcing is a simple temperature extrapolation that neglects these meteorological influences. The PDD model is likely inappropriate to this site. We use literature values for the melt factors, derived from Greenland

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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

different temperatures and moisture contents, by forcing the ascent/descent of advected air masses over terrain and by altering the turbulent heat fluxes between the free atmosphere and the surface. However, no consistent relationships were found between wind components and lapse rates. Daily average time series for the selected NARR variables were created for each glacier by averaging over a six-gridcell domain (96 km by 64 km) centered over each glacier. All time series were generated for the period

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