HR: 08:10h
AN: C11C-01 INVITED     [Abstracts]
TI: Twentieth Century Northern Hemisphere Snow Cover: Observations and Results from AGCMs and AOGCMs
AU: * Frei, A
EM: afrei@hunter.cuny.edu
AF: Department of Geography, Hunter College, Graduate Center, City University of New York, 695 Park Avenue, New York, NY 10021 United States
AB: Continental scale snow cover varied significantly during the twentieth century. In this presentation we will review (1) what is known about historical variations in large scale snow extent and snow mass over the Northern Hemisphere, and (2) how well climate models simulate those variations. Observational results, derived from both remotely sensed as well as in situ observations, indicate significant interannual and decadal scale variability, including a seasonal shift in North American snow cover during the twentieth century. Model evaluations include simulations from both Atmospheric General Circulation Models (AGCMs) and coupled Atmosphere-Ocean General Circulation Models (AOGCMs). AGCM results are taken from experiments performed using 18 models participating in the second phase of the Atmospheric Model Intercomparison Project (AMIP-2) with a time domain spanning 1979-1995. AOGCM results are taken from a recent suite of output from eight models participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) (scheduled for release some time in 2006-2007) with a time domain spanning the entire century. In general, GCMs capture the seasonal timing of snow accumulation and ablation reasonably well. However, neither interannual nor decadal scale variations in simulations correlate with observations; and, observed linkages between Eurasian snow extent and atmospheric circulation are not captured by AGCMs. Furthermore, significant between-model variability is found in every aspect of the simulations, including biases at all spatial scales. Median model results tend to be closer to observation-based estimates than results from any particular model.
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1833 Hydroclimatology
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
SC: Cryosphere [C]
MN: Fall Meeting 2005