Grantee Research Project Results
Final Report: Particulate Matter Prediction and Source Attribution for U.S. Air Quality Management in a Changing World
EPA Grant Number: R835876Title: Particulate Matter Prediction and Source Attribution for U.S. Air Quality Management in a Changing World
Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Dickerson, Russell R. , Tao, Zhining , He, Hao
Institution: University of Maryland - College Park , University of Illinois Urbana-Champaign , Goddard Earth Sciences Technology & Research
EPA Project Officer: Keating, Terry
Project Period: April 1, 2016 through March 31, 2019 (Extended to March 31, 2021)
Project Amount: $790,000
RFA: Particulate Matter and Related Pollutants in a Changing World (2014) RFA Text | Recipients Lists
Research Category: Air , Ecological Indicators/Assessment/Restoration , Climate Change
Objective:
The objectives of this study are to better understand how global changes in climate and emissions will affect the U.S. pollution, focusing on particulate matter and ozone, project their future trends, quantify key source attributions, and thus provide actionable information for U.S. environmental planners and decision makers to design effective dynamic management strategies, including local controls, domestic regulations and international policies, to sustain air quality improvements in a changing world. We will apply a state-of-the-science dynamic prediction system that couples global climate-chemical transport models with regional climate-air quality models over North America to determine the individual and combined impacts of global climate and emissions changes on U.S. air quality from the present to 2050 under multiple scenarios. We will quantify pollution sources and assign their attribution – natural vs. anthropogenic emissions, national vs. international agents, natural variations vs. climate changes – with associated probability and uncertainty. We will develop a timeline for the global change factors to become significant such that effective actions can be taken. Our hypothesis is that the integration of the most advanced modeling system, most updated emissions treatment, multi-scale processes representation, and multi climate-emission scenarios assessment will improve the predictive capability and result in more reliable projection of future changes in particular matter, ozone and related pollutants as well as their global and regional sources.
Summary/Accomplishments (Outputs/Outcomes):
We developed the state-of-art regional climate-air quality modeling system to understand how global changes in climate and emissions will affect the U.S. pollution, focusing on particulate matter and ozone, project their future trends and quantify key source attributions. The system consisted of the regional CWRF-CMAQ nested with the global CAM-Chem. We then applied the modeling system to conduct coupled climate-air quality simulations over the contiguous U.S. and made the following main findings directly relevant to U.S. EPA’s air quality management:
- Substantial surface ozone trends in the U.S. are projected for the 2050’s: 6-10 ppb decreases under the ‘clean’ A1B scenario and ~15 ppb increases under the ‘dirty’ A1Fi scenario. Among the total trends, regional emissions changes dominate, contributing negative 25-60% in A1B and positive 30-45% in A1Fi. Comparatively, climate change contributes positive 10-30%, while long-range transport effects account for positive 15-20% in both scenarios. The contribution to ozone projections due to differences in modeling design is regionally dependent, ranging from negative 20% to positive 25%.
- The 2050’s are projected with large PM2.5 reductions (~40% for A1B and ~20% for A1Fi scenario) in the eastern U.S., but slight to moderate increases (~5% for A1B and ~10% for A1Fi) in the western U.S. The projected increases are particularly large (up to 30%) near the southern border, suggesting that Mexico is a major source for future U.S. PM2.5 pollution. The effect from climate change alone is estimated to increase PM2.5 levels ubiquitously (~5% for both A1B and A1Fi). This climate penalty, however, is substantially smaller than effects of emissions change, especially in the eastern U.S. Future PM2.5 pollution is substantially influenced (up to -20%) by changes in SO2 emissions and moderately impacted (3-5%) by changes in NOx and NH3 emissions. The long-range transport effects are regional dependent, causing up to 10-20% decrease over the western U.S. in future summer PM2.5. Therefore, it is important to consider the relative contributions of emissions scenarios, climate conditions, and pollutant transports to the major PM2.5 components in future U.S. air quality regulation.
- Peak ozone concentrations in the summer afternoon decreased ubiquitously across the U.S., up to 0.5 ppbv yr-1 in major non-attainment areas, while concentrations in the early morning and late afternoon increased slightly. CMAQ simulated similar ozone trends together with monotonically decreasing trend (up to 0.5 ppbv yr-1) in the odd oxygen concentrations at all daytime hours. This suggests that the increased ozone in the early morning and late afternoon was likely caused by reduced NO–O3 titration, driven by continuous anthropogenic NOx emission reductions in the past decades. The CMAQ simulations revealed that, from 1990 to 2015, surface ozone production in some metropolitan areas has transited from a VOC-sensitive environment (>50% probability) to a NOx-sensitive regime.
- CMAQ simulations showed that wildfire impacts on primary pollutants such as CO were generally confined to the fire source areas but its effects on secondary pollutants like O3 spread more broadly. The fire contribution to air quality varied greatly during 1997-2016 and occasionally accounted for more than 100 ppbv of monthly mean surface CO and over 20 µg m-3 of monthly mean PM2.5 in the Northwest U.S. and northern California, two regions susceptible to frequent fires. Fire emissions also had implications on air quality compliance. From 1997 to 2016, fire emissions increased surface 8-hour O3 standard exceedances by 10% and 24-hour PM2.5 exceedances by 33% over CONUS.
- The emissions from fossil fuel use, influences air pollutants, such as ozone and particulates, and their effects on human health. A more definite transformation to fossil fuel free energy and transportation systems would greatly improve air quality throughout the world. Under this transformation, locations known for air quality non-compliance and associated health issues would be almost completely compliant by the midcentury. The significant reduction in exposure to poor air quality is a major incentive towards moving to a cleaner energy world.
Journal Articles on this Report : 6 Displayed | Download in RIS Format
Other project views: | All 8 publications | 6 publications in selected types | All 6 journal articles |
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He H, Liang X-Z, Lei H, Wuebbles DJ. Future U.S. ozone projections dependence on regional emissions, climate change, long-range transport and differences in modeling design. Atmospheric Environment 2016;128:124-133. |
R835876 (2016) R835876 (2017) R835876 (2018) R835876 (2019) R835876 (Final) R833373 (Final) |
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He H, Liang X-Z, Wuebbles DJ. Effects of emissions change, climate change and long-range transport on regional modeling of future U.S. particulate matter pollution and speciation. Atmospheric Environment 2018;179:166-176. |
R835876 (2017) R835876 (2018) R835876 (2019) R835876 (Final) |
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He H, Liang XZ, Sun C, Tao Z, Tong DQ. The long-term trend and production sensitivity change in the US ozone pollution from observations and model simulations. Atmospheric Chemistry & Physics 2020;20(5): 3191-3208. |
R835876 (2019) R835876 (Final) |
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Tao Z, He H, Sun C, Tong D, Liang XZ. Impact of fire emissions on US air quality from 1997 to 2016-a modeling study in the satellite era. Remote Sensing 2020;12(6):913. |
R835876 (2019) R835876 (Final) |
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Sun C, Liang XZ. Improving US extreme precipitation simulation: Sensitivity to physics parameterizations. Climate Dynamics 2020;54:4891-4918. |
R835876 (2019) R835876 (Final) |
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Sun C, Liang XZ. Improving US extreme precipitation simulation: Dependence on cumulus parameterization and underlying mechanism. Climate Dynamics 2020:1-28. |
R835876 (2019) R835876 (Final) |
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Relevant Websites:
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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
- 2019 Progress Report
- 2018 Progress Report
- 2017 Progress Report
- 2016 Progress Report
- Original Abstract
6 journal articles for this project