Transient greenhouse gas and sulfate aerosol forcing of regional climate change for the continental United States

Nested regional climate models are one tool that can be used to construct high spatial resolution climate change scenarios for use in impact studies and for furthering our understanding of regional scale climate processes. We are producing a series of high resolution climate change simulations over the continental U.S. using the latest version of the NCAR regional climate model (RegCM). These simulations include the effects of both increasing greenhouse gas concentrations and anthropogenic sulfate aerosols (direct effect only). The driving lateral boundary conditions for the RegCM are taken from NCAR Climate System Model (CSM) simulations of the current climate and of two different possible trajectories of future changes in greenhouse gases and aerosols, for the years 2080 to 2100.

We will compare the present-day climate simulated by the RegCM and the CSM with observations to determine the "value-added" by the nested model downscaling approach. In addition, the RegCM and CSM simulated climatic responses to greenhouse gases and aerosols for the future climate will be compared. Both comparisons will focus on hydrometeorological variables most relevant to impacts research.