Impacts of Global Climate and Emissions Changes on U.S. Air Quality (Ozone, Particulate Matter, Mercury) and Projection Uncertainty

EPA Grant Number: R833373
Title: Impacts of Global Climate and Emissions Changes on U.S. Air Quality (Ozone, Particulate Matter, Mercury) and Projection Uncertainty
Investigators: Liang, Xin-Zhong , Caughey, Michael , Kunkel, Kenneth , Williams, Allen , Wuebbles, Donald J.
Current Investigators: Liang, Xin-Zhong , Caughey, Michael , He, Hao , Kunkel, Kenneth , Lei, Hang , Su, Senjian , Williams, Allen , Wuebbles, Donald J.
Institution: University of Maryland
Current Institution: University of Maryland - College Park
EPA Project Officer: Chung, Serena
Project Period: April 15, 2007 through April 14, 2011 (Extended to April 14, 2013)
Project Amount: $900,000
RFA: Consequences of Global Change For Air Quality (2006) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air


The Objective of this study is to quantify and understand the impacts and uncertainties of global climate and emission changes, from the present to 2050 and 2100, on U.S. air quality, focusing on ozone, particulate matter and mercury. The original contribution of this research will derive from the application of a unique, state-of-the-art, well-established ensemble modeling system that couples a global climate-chemical transport component with a mesoscale regional climate-air quality component over North America. Both components incorporate multiple alternative models representing the likely range of climate sensitivity and chemistry response under the conceivable emissions scenarios to rigorously assess the result uncertainty. Each will be enhanced to contain a fully coupled model to study climate-aerosol interactions, focusing on how they affect U.S. air quality at the present and in the future. Resolution is further refined in Northeast, Midwest, Southeast, California and Texas, where high probabilities of air quality violations and large sensitivities to climate changes are anticipated.


The Approach is to conduct 3 primary sets of experiments by the ensemble modeling system to achieve the proposed objective. Historical simulations of climate and air quality for the recent past will first be conducted for system validation and bias identification, and also used as the baseline reference for future projections. Future projections for 2050 and 2100 will then be made to quantify the individual and combined impacts of global climate and emissions changes on U.S. air quality. Finally, sensitivity experiments will refine understanding of relationships with major contributing source regions and types, and uncertainties associated with key conclusions. All experiments will focus on April-October when most air quality episodes occur (except for sensitivity studies on the PM and mercury annual cycle), and integrate for a period of 5-10 years to obtain reasonably robust statistics. Subsequent diagnostic studies will identify possible future changes, and their climate and emissions causes, in the frequency, duration, and extreme pollutant concentrations of adverse air quality episodes over the U.S.

Expected Results:

Through the proposed application of this unique ensemble modeling system, we will make a major contribution to quantify the effect and uncertainty of global changes on U.S. air quality. The advanced state of the system components will result in a more complete scientific understanding of complex interactions among global climate and emissions and U.S. air quality across a full range of spatial and temporal scales. We will build on recent achievements of our ozone study, including a developed modeling system, viable experiment design, effective modeling strategy and objective diagnostic approach, for ozone consolidation, aerosol elaboration and mercury exploration studies for use in designing future effective emission control strategies to meet the national standards.

Publications and Presentations:

Publications have been submitted on this project: View all 20 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 20 journal articles for this project

Supplemental Keywords:

ambient air, acid deposition, mobile sources, tropospheric, precipitation, VOC, metals, solvents, oxidants, nitrogen oxides, sulfates, organics, acid rain, effluent, discharge, environmental chemistry, hydrology, mathematics, climate models,, RFA, Air, climate change, Air Pollution Effects, Atmosphere, air quality modeling, environmental monitoring, particulate matter

Progress and Final Reports:

  • 2007 Progress Report
  • 2008 Progress Report
  • 2009 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report
  • Final Report