Grantee Research Project Results
2006 Progress Report: Impacts of Global Climate and Emission Changes on U.S. Air Quality
EPA Grant Number: R830963Title: Impacts of Global Climate and Emission Changes on U.S. Air Quality
Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Williams, Allen , Huang, Ho-Chun , Zhu, Jinhong , Lin, Jintai , Hayhoe, Katharine , Patten, Ken , Kunkel, Kenneth , Caughey, Michael , Tao, Zhining
Current Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Huang, Ho-Chun , Williams, Allen , Caughey, Michael , Kunkel, Kenneth , Zhu, Jinhong , Patten, Ken , Hayhoe, Katharine , Lin, Jintai , Tao, Zhining
Institution: University of Illinois Urbana-Champaign
EPA Project Officer: Chung, Serena
Project Period: March 23, 2003 through March 22, 2006 (Extended to September 22, 2007)
Project Period Covered by this Report: March 23, 2006 through March 22, 2007
Project Amount: $900,000
RFA: Assessing the Consequences of Global Change for Air Quality: Sensitivity of U.S. Air Quality to Climate Change and Future Global Impacts (2002) RFA Text | Recipients Lists
Research Category: Air , Climate Change , Air Quality and Air Toxics
Objective:
Our interest is to better understand how global changes in climate and anthropogenic emissions affect U.S. air quality, especially tropospheric ozone (O3) and fine particulate matter (PM2.5). The ultimate goal is to account for both effects to enable state and local air quality planners to design realistic and effective emission control strategies to meet the National Ambient Air Quality Standards (NAAQS). Our research objective is to apply a state-of-the-art integrated modeling system that nests a global climate-chemical transport model (GCCT) with a regional climate-air quality model (RCAQ) over North America to quantify the individual and combined impacts on U.S. air quality of global climate and emission changes, from the present to 2020, 2050 and 2100. The RCAQ further includes 4 high-resolution subdomains over the U.S. Northeast, Midwest, West Coast and Texas for a more detailed assessment of these impacts on local surface ozone, PM2.5, and their precursors. These are the target areas where high probabilities of exceeding the NAAQS for ozone and PM2.5 are anticipated. The objective will be accomplished by 3 primary sets of experiments. Historical simulations of climate and air quality will first be conducted for system validation and for use as a baseline reference for future projections. Future projections for 2020, 2050 and 2100 will then be made, where the system incorporates scenarios of global changes in climate and/or emissions (3 runs per period) to quantify the individual and combined impacts of global climate and emission changes on U.S. air quality. The 3rd set is sensitivity experiments to determine dominant source regions and types (by adding perturbations in the U.S. or global emission inventories), relative roles of episodic transport versus mean background elevation (using transient or mean chemical inflows in RCAQ), as well as uncertainties associated with key conclusions.
Progress Summary:
- We have demonstrated that the regional climate model (RCM), CMM5, captures the spatial pattern and temporal variation of the dominant patterns and produces an improved simulation of precipitation and temperature in all seasons. The large RCM sensitivity to the choice of the cumulus parameterization have important consequences for the CMM5 applications in seasonal-interannual climate prediction, future climate change projection and impacts studies including air quality modeling. Our results have shown that a two-member ensemble based on the CMM5 simulations using the GR and KF cumulus parameterizations with geographically distributed optimal weights is superior to both individual members because there exist distinct regions where one scheme is persistently more skillful than the other and thus supplies independent information for the composite improvement.
- We have demonstrated that the biases in simulating the present climate can be systematically propagated into the projected future climate at regional scales. This conclusion is based on the existence of systematic links between the present climate biases and future change projections among a combination of two RCMs (CMM5 using the GR and KF cumulus schemes) as driven by two GCMs (PCM and HadCM3) under the present-day condition and 4 IPCC SRES emissions scenarios (B1, B2, A2, A1Fi). Therefore, it is highly questionable that a biased GCM projection of future climate changes can be directly applied for impact studies at regional to locale scales. In this regard, the RCM downscaling with a finer resolution and more complete physics representation significantly reduces the driving GCM biases and thus enhances the credibility of the future climate change projections. Since PCM and HadCM3 represent respectively the low and high climate sensitivity among the major GCMs used in the IPCC climate change assessment, while the 4 scenarios vary from low, medium to high emissions, their combinations depict the likely range of future climate change projections, justifying the robustness of our finding.
- We have demonstrated that the global CTM, MOZART, reproduces the seasonal mean ozone diurnal cycles fairly well over five major U.S. regions: the Northeast, the Midwest, the Southeast, California and the Southwest. The patterns of the morning minimum and the afternoon maximum are captured very well with little phase shift, and the nighttime ozone reductions are simulated reasonably well. The overall model physics/chemistry and thus performance are fairly reliable in current applications including the simulations of global pollution change, long-range transport and future pollution changes. We have also found significant impacts of meteorological inputs upon the ozone modeling. The morning ozone minimum is best simulated with ERA40, while the evening ozone decline seems to be best simulated with NCEP R-2. With ERA40, the increase of horizontal resolution from T62 to T106 significantly improves the simulations of morning ozone minimum with a reduction of bias around 10–20 ppb. In addition, the updated POET emissions improve the global modeling consistently along the diurnal cycle.
- We have demonstrated that the regional AQM produced good qualitative simulations of several important features, including the diurnal cycle and multi-day periods of high O3 concentrations resulting from transient weather regimes. The AQM produced a realistic diurnal seasonal mean O3 distribution over the Northeast and Midwest sub-domains. However, underestimation of nighttime O3 concentrations occurs in the vicinity of metropolitan areas, and overestimation of daytime O3 of 5.0 ppb was found in the Northeast sub-domain. A fairly good simulation was found in the Midwest sub-domain with the bias of 1.4 ppb. AQM simulations successfully reproduced most of the monthly and seasonal mean values of daytime O3 in the New York, Washington D.C., and Chicago areas. The monthly and seasonal mean characteristics in the two sub-domains also could be captured by the modeling system. This suggests that our regional modeling system is capable of performing climate change/air quality assessments.
- We have found that, with climate change only and no changes in biogenic emissions, the differences in the ozone change simulated by MOZART between A1Fi and B1 are mainly in the spatial patterns rather than magnitudes. Under both scenarios, changes in summer by 2095–2099 relative to the present day are generally within 6 ppb, mostly less than 3 ppb, over the U.S. The ozone increases in much of the eastern U.S. under A1Fi and in the west under B1. The ozone reductions in the coastal areas are more significant under A1Fi. The number of high-end ozone days greatly increases over the Midwest and decreases over the coastal regions of California. The ozone increases in inland areas were highly attributable to the increased air temperature and the ozone decreases in coastal areas were highly attributable to the increased dilution by the marine air mass. The magnitudes of ozone change greatly differ between A1Fi and B1 when the changes in biogenic emissions included. Effects of climate change on ozone are largely masked out by those of changes in biogenic emissions over most areas. When both climate and biogenic emissions changes are imposed, summertime mean ozone levels rise by 3–12 ppb under A1Fi and 0–6 ppb under B1, and two thirds of the summer days are projected to suffer from the high-end ozone under A1Fi. These results are elaborated by the refined regional AQM simulation study (below).
- We have found that the U.S. regional surface O3 responds differently to the emissions and climate changes projected for 2050 under the different IPCC emissions scenarios. Under the A1Fi scenario (“dirty” outlook), the summer average daily mean and maximum 8-hour O3 concentrations show upward trends in vast rural areas in the U.S. Under the B1 scenario (relatively “clean” outlook), O3 quantities decline in broad rural areas. In major cities and metropolitan areas, large reductions in NOx emissions tend to increase surface O3 concentrations. The projected emissions changes are largely responsible for future U.S. O3 changes in more than 61% area of the contiguous U.S. under the B1 scenario, while the projected climate changes are the dominant factor in 46% area under the A1Fi scenario. The biogenic emissions changes induced by the projected climate changes are dominant in the Northeast under both scenarios, contribute largely (moderately) in the Midwest under the A1Fi (B1) scenario, and are a minor factor in California and Texas.
- We have found that the greatest influence (12 to 16 ppbv) of transboundary precursor emissions on daily 8-hour maximum ozone concentrations occurs: (a) in northwestern Washington state, (b) along the southern shore of Lake Ontario, and (c) in other limited areas very near the boundaries, and the lesser one (4 to 12 ppbv) is found extending along the lengths of the Canadian and Mexican borders, as well as in a distinct mid-content band extending approximately from New Mexico through western Texas, Oklahoma, Kansas and Iowa up to Minnesota. Areas showing little influence (0 to 4 ppbv) include most of California and the intermountain West, as well as eastern Texas and a large section of Gulf and southeastern states. The regional flow governed by the prevailing Bermuda high pressure system directs precursor emissions from Mexico away from major metropolitan areas, such as Houston–Galveston–Port Arthur and Dallas–Fort Worth. On the other hand, the prevailing westerly flow and the blocking of the Bermuda high result in transport of additional emissions from Ontario and Quebec into the Northeast.
- We have found that the large RCM sensitivity to the cumulus parameterization with strong regional dependence has an important impact on the simulations of BVOC emissions and surface O3 concentrations. In the California and Texas sub-domains, the AQM shows a similar skill to simulate regional O3 concentrations using the RCM meteorology with both GR and KF schemes. In the Midwest and Northeast sub-domains, warmer temperature simulated using the KF versus GR cumulus scheme leads to higher surface O3 concentrations. In Midwest, Northeast, and Texas sub-domains, the AQM simulated occurrence of high O3 (>80 ppb of 8-hour average) driven by the RCM meteorology approximately doubles when using the KF instead of GR cumulus scheme, indicating a large uncertainty in projecting future O3 exceedance. The great sensitivity of BVOC emissions and surface O3 concentrations to the choice of the RCM cumulus parameterization poses a challenge on how to interpret future air quality. The modeling community must consider the uncertainty associated with alternative model configurations in projecting future air quality scenarios, based on which policy makers may integrate in their decisions a more realistic range of possible air quality changes and impacts.
- This STAR project is closing. We have accomplished all the tasks as originally proposed and, in many aspects (for example, model experiments and peer-reviewed papers), our research productivity exceeds the original expectation. With the support of this EPA STAR project, we have published 10 articles, revised 2 articles and submitted 2 articles in major peer-reviewed journals, and made over 30 presentations in major conferences, including invited talks at the U.S. Climate Change Science Program workshop, American Association for the Advancement of Science, American Geophysics Union and American Meteorology Society annual meetings. The results have been and are being used as a scientific basis for several important national and regional assessments on climate changes, including the USEPA Assessment of Climate Change Impacts on Air Quality, the US Climate Change Science Program Assessment, the Northeast Climate Impacts Assessment and the Chicago Regional Climate Change Assessment. The remaining activity in FY2008 is to continue disseminating our results to the public, through publications in peer-reviewed journals and books and also presentations at major conferences and institutions.
Future Activities:
This project is closing. The main activity in FY2008 is to disseminate our results from this STAR project to the public, through publications in peer-reviewed journals and books and also presentations at major conferences and institutions. In particular, we plan to publish our findings in the following topics:
- RCM and GCM projections of heat waves
- Impacts of GCM present climate biases on future change projections
- Impacts of emissions in Canada and Mexico on the USA air quality
- Future ozone change: upper and lower limits and uncertainty
- Impacts of continental and intercontinental transports on the U.S. ozone concentrations
Journal Articles on this Report : 12 Displayed | Download in RIS Format
| Other project views: | All 37 publications | 18 publications in selected types | All 18 journal articles |
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Huang H-C, Liang X-Z, Kunkel KE, Caughey M, Williams A. Seasonal simulation of tropospheric ozone over the Midwestern and Northeastern United States:an application of a coupled regional climate and air quality modeling system. Journal of Applied Meteorology and Climatology 2007;46(7):945-960. |
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Kunkel KE, Liang X-Z. GCM simulations of the climate in the central United States. Journal of Climate 2005;18(7):1016-1031. |
R830963 (2003) R830963 (2004) R830963 (2005) R830963 (2006) R830963 (Final) |
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Kunkel KE, Liang X-Z, Zhu J, Lin Y. Can CGCMs simulate the twentieth-century "warming hole" in the central United States? Journal of Climate 2006;19(17):4137-4153. |
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Kunkel KE, Huang H-C, Liang X-Z, Lin J-T, Wuebbles D, Tao Z, Williams A, Caughey M, Zhu J, Hayhoe K. Sensitivity of future ozone concentrations in the northeast USA to regional climate change. Mitigation and Adaptation Strategies for Global Change 2008;13(5-6):597-606. |
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Liang X-Z, Li L, Dai A, Kunkel KE. Regional climate model simulation of summer precipitation diurnal cycle over the United States. Geophysical Research Letters 2004;31(24):L24208 (4 pp.). |
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Liang X-Z, Pan J, Zhu J, Kunkel KE, Wang JXL, Dai A. Regional climate model downscaling of the U.S. summer climate and future change. Journal of Geophysical Research--Atmospheres 2006;111(D10):D10108 (17 pp.). |
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Liang X-Z, Xu M, Kunkel KE, Grell GA, Kain JS. Regional climate model simulation of U.S.-Mexico summer precipitation using the optimal ensemble of two cumulus parameterizations. Journal of Climate 2007;20(20):5201-5207. |
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Lin J-T, Patten KO, Hayhoe K, Liang X-Z, Wuebbles DJ. Effects of future climate and biogenic emissions changes on surface ozone over the United States and China. Journal of Applied Meteorology and Climatology 2008;47(7):1888-1909. |
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Tao Z, Williams A, Huang H-C, Caughey M, Liang X-Z. Sensitivity of U.S. surface ozone to future emissions and climate changes. Geophysical Research Letters 2007;34(8):L08811 (5 pp.). |
R830963 (2006) R830963 (Final) R831449 (2006) R831449 (Final) |
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Tao Z, Williams A, Huang H-C, Caughey M, Liang X-Z. Sensitivity of surface ozone simulation to cumulus parameterization. Journal of Applied Meteorology and Climatology 2008;47(5):1456-1466. |
R830963 (2006) R830963 (Final) R831449 (Final) |
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Zhu J, Liang X-Z. Regional climate model simulation of U.S. soil temperature and moisture during 1982-2002. Journal of Geophysical Research-Atmospheres 2005;110(24):D24110 (12 pp.). |
R830963 (2004) R830963 (2005) R830963 (2006) R830963 (Final) |
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Zhu J, Liang X-Z. Regional climate model simulations of U.S. precipitation and surface air temperature during 1982–2002: interannual variation. Journal of Climate 2007;20(2):218-232. |
R830963 (2006) R830963 (Final) |
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Supplemental Keywords:
climate change, emission, pollutant transport, scale interaction, ozone, nitrogen oxides, sulfate, particular matter, regional climate model, air quality model,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Air Quality, Air Pollutants, Chemistry, climate change, Air Pollution Effects, Monitoring/Modeling, Atmospheric Sciences, Environmental Engineering, Atmosphere, ambient aerosol, environmental monitoring, anthropogenic stress, atmospheric dispersion models, aerosol formation, atmospheric particulate matter, environmental measurement, meteorology, climatic influence, emissions monitoring, future projections, air quality models, ozone, global change, atmospheric transport, greenhouse gases, climate models, atmospheric aerosol particles, airborne aerosols, environmental stress, regional emissions model, climate model, ecological models, greenhouse gas, aerosols, atmospheric chemistry, climate variability, Global Climate Change, ambient air pollutionRelevant Websites:
http://www.sws.uiuc.edu/atmos/modeling/caqims/ Exit
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.