Simulated impact of vegetation across the North American monsoon region in CCSM3.5

The influence of vegetation on the climate of the North American monsoon region is examine using the National Center for Atmospheric Research Community Climate System Model Version 3.5 (NCAR CCSM3.5). Initial value ensemble experiments are performed in which the vegetation cover fraction over the NAMR is reduced by 0.2 and the intra-annual climatic response is assessed probabilistically in each one-year ensemble experiment. Changes in the surface radiation budget include decreases in sensible and latent heat fluxes and increases in upward longwave and downward shortwave radiation fluxes, with small net changes in surface albedo. The climatic responses to reduced vegetation cover fraction include increased ground and surface air temperature, a dampened hydrologic cycle with decreased evaporation, precipitation, and cloud cover, and enhanced atmospheric subsidence. Also, the monsoon season over the Southwest United States shifts earlier in the year. Within the North American monsoon region, the most robust vegetation feedbacks to climate are found over woody landscapes.