Grantee Research Project Results
2009 Progress Report: Impacts of Global Climate and Emissions Changes on U.S. Air Quality (Ozone, Particulate Matter, Mercury) and Projection Uncertainty
EPA Grant Number: R833373Title: Impacts of Global Climate and Emissions Changes on U.S. Air Quality (Ozone, Particulate Matter, Mercury) and Projection Uncertainty
Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Williams, Allen , Lei, Hang , Zhu, Jinhong , Hayhoe, Katharine , Patten, Ken , Kunkel, Kenneth , Caughey, Michael , Su, Shenjian
Current Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Williams, Allen , Lei, Hang , He, Hao , Kunkel, Kenneth , Caughey, Michael , Su, Senjian
Institution: University of Illinois Urbana-Champaign
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 Period Covered by this Report: April 15, 2009 through April 14,2010
Project Amount: $900,000
RFA: Consequences of Global Change For Air Quality (2006) RFA Text | Recipients Lists
Research Category: Climate Change , Air
Objective:
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 USA 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 USA air quality at the present and in the future.
We propose to conduct three 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 then will be made to quantify the individual and combined impacts of global climate and emissions changes on USA 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 USA.
Through the proposed application of this unique ensemble modeling system, we will make a major contribution to a key goal of the EPA Global Change Research Program to quantify the effect and uncertainty of global changes on USA 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 USA 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.
Progress Summary:
- We have completed the RCM integration driven by the CCSM3 for both 2045-2055 and 2090-2099 under the IPCC B1, A1B, and A1FI emissions scenarios. The result indicates that the RCM downscaling improves the present-day regional climate simulations (more realistic than the driving GCMs) and provides likely more credible (than GCMs) projections of future regional climate changes. We have found that the model biases in the present-day climate simulation depend on geographic regions and climate regimes and can be systematically propagated into future regional climate projections. Compared to surface air temperature, simulated precipitation has larger biases and wider spreads over Texas and the Southeast than the Midwest and California.
- We have investigated future changes in the annual cycles of surface air temperature and precipitation for the broad subdomains of the Northeast, Midwest, Southeast, California, and Texas, projected by GCMs and downscaled by RCMs. In 2050s, the projected warming trends are shown clearly in all subdomains throughout the entire year except for the transition months (February and November), while precipitation is projected with slightly dry trends. The warming trends are significantly amplified in the 2100s. The projected trends of both surface air temperature and precipitation scatter more widely over all subdomains in the 2100s as compared with the 2050s.
- We have demonstrated that the RCMs’ downscaling reduces significantly driving GCMs’ present-climate biases and narrows inter-model differences in representing climate sensitivity and hence in simulating the present and future climates. Major model present-climate biases are systematically propagated into future-climate projections at regional scales. The result suggests that the nested RCM-GCM approach that offers skill enhancement in representing the present climate also likely provides higher credibility in downscaling the future climate projection.
- We have conducted RCM simulations to evaluate the probability of heat waves of unprecedented severity by the end of the 21st Century if a high emissions path is followed. All of the RCM simulations for high emissions, including the one driven by the low-climate sensitivity CGCM, produce major increases in heat wave intensity and frequency. If a lower emissions path is followed, the outcomes range from quite small changes to substantial increases in intensity. In addition to the direct effects of heat, urban air quality can also be adversely affected by heat waves because of the temperature dependence of relevant chemical reactions, causing secondary impacts on health. The projected more frequent and/or intense heat waves will have increased risks of adverse health consequences.
- We have investigated the impact of the Bermuda high on the climate of the U.S. and the distribution and transport of ozone by comparing the simulations with observation. The study indicates that the Bermuda high related closely to the LLJ plays a significant role. It also demonstrates that multiple simulations by different regional models under different scenarios are needed to develop robust conclusions about climate impacts on air quality, given the uncertainties of the model and the future scenarios.
- We have completed the CMAQ simulation with CAM-Chem lateral boundary condition (LBC) for present (1995-1999) and summer of future (2048-2052) years under the IPCC A1FI and A1B scenarios with climate and/or emission changes. The result indicates that with CAMChem LBC, CMAQ simulation ability is improved. We found that Mexico is a long-range transport source of ozone over western U.S.
- We have built an Hg vertical profile at the boundary of the simulation area, and we have carried out a CMAQ experiment using NCEP reanalysis II meteorology data during 2001-2002. As compared with the NADP MDN measurements, the model caught the pattern in the Northeast but underestimated the wet deposition in the Southeast, especially in Florida.
- The upper limit of ozone-vegetation interaction-caused ozone concentration change is assessed under the current pollution level in each of the EPA Regions. The observed ozone injury to forest plants data by EPA is used as the reference of U.S. plant injury assessment. 5-year (1995-1999) average surface ozone concentration simulated by the global-scale Community Atmospheric Model with Chemistry (CAM-Chem) is used as the current pollution reference. The estimated maximum uncertainty caused by plant injury with current surface ozone concentration is less than 0.5 ppb.
- A series of sensitivity experiments based on CAM-Chem isdesigned to explore the relationships of changes of sulfate and nitrate aerosols. Sensitivity experiments include SOx emission reduced to: 10%, 20%, and 50% of original emissions to see the changes in nitrate aerosol concentration changes. The result shows that nitrate concentration change shows nonlinear characteristics to precursor (NOx) emissions. In summer, it is highly affected by SOx emissions due to a chemical competition mechanism. In winter, less SOx emission and enough ammonia emission make the nitrate concentration stable to precursor emission.
- A global mercury module is developed in the UIUC version of the CAM-Chem to simulate the current status and future changes of the mercury (Hg) cycle in the atmosphere. The mercury chemistry involved in this module includes gas phase reactions and heterogeneous reactions in aqueous phase with the present clouds. The current mercury emission includes emissions from anthropogenic sources, soil sources, ocean, biofuel, and volcanoes. The simulation on current atmospheric mercury pollution presents the right wet deposit pattern to the observation by the national atmospheric deposition program. The time series comparison to observation on four stations also supported the model simulation.
- Projection of 2050 mercury emission to the atmosphere follows the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) (IPCC, 2001). With the projected emissions, CAM-Chem is implemented to simulate the future mercury pollutions under each scenario. The largest increase of global mercury emission in 2050 is estimated under the A1FI scenario. The general surface concentration changes of elemental mercury (Hg0), reactive mercury (Hg2), and particulate mercury (HgP) over the continental United States are around 2.3 times more than the current concentration. The results under the A1B scenario are a little lower. The increasing ratio is around 2 times more. Both emission and concentration changes under the B1 scenario are the smallest; however, the concentrations are still nearly doubled based on the current value. Although the emissions over the United States region are reduced, the long-range transport from Asia increased more than the reduction. The results also show the Hg2 ratio in total mercury will increase in 2050 due to the surface temperature increase.
- A Physical Dust Aerosol Model (PDAM) is developed by incorporating the wind erosion physics of Shao [2008] and various other improvements within the UIUC version of CAMChem. The coupled system is used to simulate the current dust climate, including individual dust events. The numerical results are compared with meteorological and satellite data, and the simulations agree well with the observations. In addition, the contributions of mineral dust on the level of U.S. particulate matter (PM) are analyzed. The comparison of PM results with dust runs and without dust runs show that accurate mineral dust simulations can effectively improve both PM10 and PM2.5 simulations.
- We have completed project tasks in our original proposal, and in some cases we have accomplished more than originally proposed. With the support of this EPA STAR project in the last year, we have so far published four articles and almost completed four manuscripts for publication in peer-reviewed journals.
Future Activities:
- Diagnose outputs to quantify relative roles of global climate and emission changes.
- Diagnose outputs to study the impacts of climate and emission changes on U.S. air quality.
- Publish the results in peer-reviewed journal articles, including:
- Future USA ozone projections due to global climate and/or emissions changes.
- Future USA PM2.5 projections due to global climate and/or emissions changes.
- Future USA dry and wet deposition projections for nitrate.
- Future USA climate change projections: uncertainty assessment and reduction.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 21 publications | 21 publications in selected types | All 21 journal articles |
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Hayhoe K, Robson M, Rogula J, Auffhammer M, Miller N, VanDorn J, Wuebbles D. An integrated framework for quantifying and valuing climate change impacts on urban energy and infrastructure: a Chicago case study. Journal of Great Lakes Research 2010;36(Suppl 2):94-105. |
R833373 (2009) R833373 (Final) |
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Hayhoe K, VanDorn J, Croley II T, Schlegal N, Wuebbles D. Regional climate change projections for Chicago and the US Great Lakes. Journal of Great Lakes Research 2010;36(Suppl 2):7-21. |
R833373 (2009) R833373 (Final) |
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Kunkel KE, Liang X-Z, Zhu J. Regional climate model projections and uncertainties of U.S. summer heat waves. Journal of Climate 2010;23(16):4447-4458. |
R833373 (2009) R833373 (Final) |
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Wang X, Liang X-Z, Jiang W, Tao Z, Wang JXL, Liu H, Han Z, Liu S, Zhang Y, Grell GA, Peckham SE. WRF-chem simulation of East Asian air quality: sensitivity to temporal and vertical emissions distributions. Atmospheric Environment 2010;44(5):660-669. |
R833373 (2009) R833373 (Final) |
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Supplemental Keywords:
climate change, emission, uncertainty, pollutant transport, ozone, particulate matter, mercury, aerosol, cloud, radiation, regional climate model, air quality model, RFA, Air, climate change, Air Pollution Effects, Atmosphere, air quality modeling, environmental monitoring, particulate matterRelevant Websites:
Climate, Air Quality and Impact Modeling System (CAQIMS)Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- Final Report
- 2011 Progress Report
- 2010 Progress Report
- 2008 Progress Report
- 2007 Progress Report
- Original Abstract
21 journal articles for this project