BLM REA COP 2010 Difference of Average Winter (Jan-Mar) Precipitation (2045-2060 vs 1968-1999) Simulated by RegCM3 with GFDL Projections as Boundary Conditions (Western US)

Difference of Average Winter (Jan-Mar) Precipitation (2045-2060 vs 1968-1999) simulated by RegCM3 with GFDL projections as boundary conditions. Units are millimeters. These data were generated by the regional climate model RegCM3 with boundary conditions from a GCM future climate projections. The data were downscaled statistically by calculating differences (anomalies) between the RegCM3 results with GCM-driven boundary conditions for 1968-99 and those for a future period, in this case 2015-2030. The anomalies were added (temperatures) or multiplied (precipitation) to a climate baseline from PRISM (Parameter-elevation Regressions on Indepenent Slopes Model - prism.oregonstate.edu) data based on historical observations. The PRISM baseline was calculated as average monthly climate conditions for 1968-1999 reprojected the results to the BLM Albers 4km grid. PRISM data are provided in a 2.5 arc-minute lat-lon grid. This dataset represents the difference between downscaled data for 2045-2060 and 1968-1999 means. RegCM3 is the third generation of the Regional Climate Model originally developed at the National Center for Atmospheric Research during the late 1980s and early 1990s. Details on current model components and applications of the model can be found in numerous publications (e.g., Giorgi et al, 2004a,b, Pal et al, 2007), the ICTP RegCNET web site (http://users.ictp.it/RegCNET/model.html), and the ICTP RegCM publications web site (http://users.ictp.it/~pubregcm/RegCM3/pubs.htm). The Western North America domain has a horizontal grid spacing of 15 km and 18 vertical levels. RegCM3 requires time-dependent lateral (wind, temperature, and humidity) and surface [surface pressure and sea surface temperature (SST)] boundary conditions that are updated every 6 hours of simulation. Lateral boundary conditions are derived from General Circulation Model (GCM) output or observations (e.g. NCEP). Additional information can be found at: http://regclim.coas.oregonstate.edu/. Global climate simulations from the GFDL CM 2.0 were part of a suite of model output used in the Climate Model Inter-comparison Project (CMIP) and the IPCC AR4. GFDL has a long development history and has been widely applied to climate research. Details and documentation of the model can be found following links on the CMIP website located at: http://www pcmdi.llnl.gov/ipcc/model_documentation/ipcc_model_documentation.php.