Air Quality in the U.S. under Future Climate and Emission Scenarios

Regional air quality can be affected by a changing climate. In this study, simulation results of the NCAR's Community Climate System Model (CCSM) under the Intergovernmental Panel on Climate Change (IPCC) A1B scenario are downscaled to provide initial and boundary conditions for regional meteorological simulations over the continental U.S. at 36-km and the eastern U.S. at 12-km using the Weather Research and Forecasting Model (WRF) version 3.2 for summer and winter months in future years (2020, 2030, 2035, 2040, 2045, and 2050). Regional air quality simulations are being conducted under future climate and emission scenarios using the U.S. Environmental Protection Agency (EPA)'s Community Multiscale Air Quality Modeling (CMAQ) system version 4.7 for the year of 2002 and the above future years. The future year simulations are being compared with WRF/CMAQ simulations for 2002 to examine the changes in major meteorological variables such as temperature, relative humidity, wind fields, precipitation, mixing heights, and atmospheric stability, as well as the resultant changes in biogenic emissions and air quality in terms of the concentrations and dry and wet deposition of major chemical species in the U.S. The interannual variability in both regional climate and air quality and their implications will also be assessed.