This project is a continuation of work performed under NSF Grant ATM-8507782, which was an investigation of snow cover effects on the atmospheric circulation over synoptic to monthly timescales. The methodology of the earlier project included both statistical analyses of synoptic-scale data and model experiments with the Community Forecast Model (CFM) of the National Center for Atmospheric Research. The tasks proposed for the renewal include (1) consolidation of observational data depicting surface boundary conditions (snow cover, sea ice, sea surface temperature) into a CFM-compatible 15-year set of weekly grids for the Northern Hemisphere, thus serving initialization as well as verification needs; (2) use of the surface boundary dataset to extend earlier CFM forecast experiments to the multiseason timescale, with particular attention given to the magnitude and physical mechanisms of Eurasian snow cover effects on the circulation; (3) experiments to assess the performance of the recently implemented surface hydrology in the NCAR CFM; and (4) and examination of the persistence of observed and simulated monthly circulation anomalies as functions of the location and other characteristics of surface boundary anomalies. This research is important because it provides a systematic approach to learning how snow cover affects weather and climate through observations applied to theory and modeling.
