(611a) Future Air Quality and Climate Change in the Eastern United States

Elevated particulate matter (PM) concentrations contribute to poor air quality throughout large parts of the United States, affecting visibility and human health. PM_2.5, particles with an aerodynamic diameter less than 2.5 μm, are particularly important as they can travel far into the human respiratory system and are therefore more dangerous than larger particles. Future changes in climate (including changes in temperature, mixing heights, rainfall, etc.) will affect urban and regional air quality, including PM­_2.5 and ozone. We investigate potential effects using the Global-REgional Climate-Air Pollution modeling System (GRE-CAPS).  GRE-CAPS couples the Goddard Institute for Space Studies (GISS) II prime general circulation / chemical transport model (GCM/CTM), the MM5 regional meteorological model, and PMCAMx-2008, a regional chemical transport model.  The Model of Emissions of Gases and Aerosols from Nature (MEGAN) was added to provide meteorologically-reactive biogenic emissions.  Meteorology from ten representative years in the 1990s (present-day) and ten from the 2050s (future) is used.  Future meteorology is based on the Intergovernmental Panel on Climate Change (IPCC) A2 scenario, detailing a heterogeneous world without a focus on sustainability.  The future model predictions of ozone levels and PM­_2.5 constituents for the Eastern US are compared to present-day distributions, averages and extremes.  Previous work by Dawson et al. (2009) covered similar ground, but lacked dynamic biogenic emissions, treated the primary organic aerosol as non-volatile and non-reactive, and simulated only the first generation of secondary organic aerosol production. In PMCAMx-2008, organic aerosol (OA) – a significant part of PM_2.5 – is simulated using the volatility basis set approach, in which primary emissions are semi-volatile and gas phase organic compounds are oxidized and result in products with lower volatility.  For this reason, special focus is given to OA changes, particularly because the OA response to climate change is more uncertain than that of other PM­_2.5 components.

References

Dawson J.P., Racherla P.N., Lynn B. H., Adams P.J., Pandis S.N., 2009. Impacts of climate change on regional and urban air quality in the eastern United States: Role of meteorology. Journal of Geophysical Research, 114, D05308, doi:10.1029/2008JD009849.