Wednesday, 12 February 2003: 3:45 PM
Snow Cover Simulations in the Second Phase of the Atmospheric Model Intercomparison Project
Simulations of regional to hemispheric scale snow covered area (SCA) and snow water equivalent (SWE) over Northern Hemisphere lands by General Circulation Models (GCMs) from the second phase of the Atmospheric Model Intercomparison Project (AMIP-2) are evaluated. GCM results are compared to a data set derived primarily from visible band satellite imagery provided by the United States National Oceanic and Atmospheric Administration; and to two new independently derived gridded data sets based on station observations over North America. With regards to SCA, at continental to hemispheric scales we find improvements over AMIP-1 models, including the elimination of temporal and spatial biases in simulations of the seasonal cycle, as well as improved simulations of the magnitude of interannual variability. At regional spatial scales, while no consistent model biases in SCA are identified over North America, two regions over Eurasia are identified where models consistently either under- or over-estimate SCA. With regards to SWE, GCM strengths and weaknesses over particular North American regions with sufficient observational data coverage will be identified. For example, over the Northern Great Plains of the United States, models do not capture the magnitude SWE during large snow years, despite the fact that simulated SCA values are close to observed.