General Circulation Models: Downscaling and Incorporation into Watershed Models.

Assessing the potential impacts of climate change on water resources through the use of General Circulation Model (GCM) output has become commonplace throughout the world.  However, outputs from GCMs are often at a scale much too coarse for local or regional assessment and thus downscaling, the process of translating GCM output to local or regional scales, must be performed. Several methods exist to downscale GCM data, including statistical and dynamic methods, which will be discussed. Recently, several downscaled GCM data warehouses have become available, allowing researchers and water resource managers interested in impact studies to easily access and download this data for their particular region.  This downscaled GCM data, however, may be in a format that is not compatible with watershed models, and thus an understanding of the data format and extraction methods is needed. This talk presents some of the common methods to downscale GCM output, as well as transforming this data for use in watershed models (specifically the Soil and Water Assessment Tool). Specific examples of GCM data and extraction throughout the western United States will be presented.