150-Year CONUS Quasi-Dynamical Downscaling with ICAR

To produce hydrological projections due to anthropogenic climate change, downscaling of general climate models (GCM) is necessary to provide information on relevant spatial and temporal scales. Here we present 12 km downscaled projected precipitation over the Contiguous United States (CONUS) from 8 CMIP5 models (Coupled Model Intercomparison Project Phase 5) for RCP4.5 and RCP8.5 from the years 2006-2100. In addition, we also downscaled historical runs (1950-2006) using the same CMIP5 models. We employed a quasi-dynamical downscaling approach with the Intermediate Complexity Atmospheric Research (ICAR) model. This model uses a complex linear model to describe the wind perturbations, with the inclusion of detailed physical schemes for advection, microphysics and land surface modeling. For input to the ICAR downscaling, the CMIP5 runs were first bias corrected against ERA-I reanalysis (1980-2005), then downscaled by WRF to a 50 km grid resolution to provide hourly input to ICAR. We will evaluate the variability of precipitation changes between the different downscaled CMIP5 models and focus on the more localized changes that can be modeled with ICAR. Furthermore, in specific regions (Pacific Northwest and in the Colorado Rockies) the snow albedo effect is evident in the ICAR downscaled simulations, where temperature changes are larger at higher elevations than lower elevations. This is specifically seen in the winter months.