Final Report: 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 , Wuebbles, Donald J. , Williams, Allen , Lei, Hang , He, Hao , Kunkel, Kenneth , Caughey, Michael , Su, Senjian
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

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 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.

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 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 the 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 United States.

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 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.

Summary/Accomplishments (Outputs/Outcomes):

  • 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. Very high spatial pattern correlations of the RCM minus GCM differences in precipitation and surface temperature between the present and future climates indicate that major model resent climate biases are systematically propagated into future climate projections at regional scales. The total impacts of the biases on trend projections also depend strongly on regions and cannot be linearly removed. 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 found that changes in intercontinental transport (ICT) of pollutants can have substantial consequences on future U.S. air quality. The projected ICT changes are primarily affected by changes in anthropogenic emissions over Europe and Asia, which may cause 3–8 ppb more (0-2 ppbv less) ozone under the A1Fi (B1) scenario in 2049 and 2099 over the western United States. The nested regional air quality model simulations show that the net increase due to the long-range transport in 2095-2099 ranges from +4% to +11% in daily maximum 8-hr average ozone concentrations. Therefore global, especially Asian, emission control is important for future U.S. pollution mitigation.
  • We have quantified the uncertainty in projecting future U.S. ozone changes by using the ensemble approach based on the nested regional modeling system. This ensemble consists of six combinations of two GCMs each with two emissions scenarios and two downscaling RCMs with different cumulus parameterizations. The result indicates a large range of uncertainties due to various model configurations and emissions scenarios. The projected daily maximum 8-hr average ozone changes range from -31% to +51%. In general, the A1Fi scenario projects a substantial increase in both surface ozone concentrations and exceedance days, while the B1 scenario results in a significant decrease. Thus, future U.S. pollution control must consider the large uncertainty in model projected trends and their sensitivities to global climate and emissions changes.
  • We have investigated the model factors that affect the simulation of the summer time U.S. surface ozone diurnal cycle in the global chemistry transport model MOZART. We have identified that the dominant factor is the representation of the planetary boundary layer (PBL) mixing, while the influence of horizontal resolutions and precursor emissions is relatively small but non-negligible. With the non-local mixing PBL scheme, a relatively high horizontal resolution (~1.1°) and updated emissions data, the MOZART is able to simulate the key characteristics of the observed ozone diurnal cycle.
  • We have implemented the latest emission processor SMOKE v2.4 and incorporated the best available anthropogenic emissions inventories as well as biogenic emissions using BELD3 for the United States, Mexico and Canada. By integrating the RCM downscaling meteorology driven by the CCSM3 simulation in 1995, we have processed the emissions on the regional modeling grids for the entire year and analyzed their diurnal cycles and seasonal variations.
  • We have improved the CMAQ representation of lateral boundary conditions. In particular, we have incorporated the dynamic relaxation procedure to integrate large-scale forcings from the CAM-Chem global simulations across the buffer zones of a specified width. Such a procedure is fully consistent with that used in the RCM climate downscaling. Wider buffer zones have been found necessary to ensure realistic RCM climate downscaling over the continental U.S. domain. It is expected to ensure realistic CMAQ air quality downscaling from the CAM-Chem. This expands, for the first time, the CMAQ ability from the long-standing method of representing the long-range chemical transport using a single cell around the domain edges. More importantly, we can now integrate the external forcings as time tendencies rather than full fields of chemical species and thus reduce the impact from the existing CAM-Chem systematic errors.
  • We have completed the CAM-Chem global chemistry transport run driven by the NCEP reanalysis II meteorology data during 2001-2002. As compared with the EPA AQS measurements, the model captures the main characteristics of the geographic distributions of surface zone, particulate matter, and three major aerosols (sulfate, ammonium, and nitrate). The CAM-Chem produces large biases in surface ozone, with a systematic overestimation of 8-32 ppb. The biases, however, have been largely reduced as compared with the previous runs driven by the CCSM3 climate. The PM10 biases are generally in the range of -24 to -32μg/m3 as compared with the EPA AQS measurements. That systematic underestimation results because the model currently does not incorporate dust transport. For PM2.5 the CAM-Chem results are 8-24 μg/m3 higher than observations over the eastern United States. In addition, the simulated current values of wet sulfate depositions agree closely with National Atmospheric Deposition Program (NADP) observations. The simulated peak value of nitrate wet deposition shows strong biases, indicating possible problems in the model representation of the nitrogen chemical cycle.
  • We have carried out sensitivity experiments using CAM-Chem to determine the impacts of future changes in anthropogenic emissions on projected U.S. air quality under the IPCC A1Fi, A1B and B1 emissions scenarios representing respectively the upper, middle and lower bounds of climate warming over the 21st century. The projected summer surface ozone changes by 2050 range from 6 to 12 ppb under A1Fi, from -2 to -20 ppb under A1B, and from -5 to -24 ppb under B1. Aerosol changes by 2050 show strong seasonal variability. Sulfate concentrations under all three scenarios show decreasing trends due to the emission control. Ammonium also shows a decreasing trend. However, nitrate concentration varies not only with NOx emissions but also with sulfate and ammonium concentration via sensitive chemical reactions. Under A1Fi, nitrate concentration almost doubled due to the predominant role of the NOx emissions increase. In contrast, under A1B and B1 with significant NOx emissions reductions, large nitrate increases are projected in the Northeast for winter. This is because the reduced sulfate coupled with increased ammonia emissions result in more ammonia available to react with nitrate, and thus total ammonia increases and nitrate aerosol concentrations can be more than double.
  • We have quantified by sensitivity experiments, from a global CTM perspective, the relative contributions from future changes of local emissions and intercontinental pollutant transport (ICT) to the U.S. ozone changes under A1fi, A1B, and B1 emission scenarios. The result shows that the impact of local emissions is much larger than that of ICT. Under A1Fi, the maximum surface zone change due to local emissions change is around 12 ppb, while transpacific transport contributes less than 5 ppb and is limited to the western United States. Under A1B and B1, the effects from local emissions changes are much larger than those from ICT. It implies that limiting local emissions are still crucial and most effective in controlling future surface ozone quality.
  • We have developed air pollution emissions inventories for 2050 and 2100 by scaling the present ones based on the IPCC’s A1Fi and A1B future emissions scenarios. We used the scaling factors derived from the OECD90 regions for the United States and Canada, and the factors based on the ALM regions for Mexico. The future inventories were then processed through SMOKE to provide speciated, gridded, and temporalized hourly emissions input for CMAQ. We have completed processing emissions for the periods of 1995–1999 and 2048–2052 using the corresponding meteorological simulations by the CCSM3-driven RCM downscaling with the Grell cumulus parameterization scheme.
  • We have conducted present full 5 years' (1995-1999) integration of CMAQ driven by the RCM meteorology downscaled from the CCSM3 simulation to evaluate the regional air quality modeling system performance. The model well simulates the AQS observed MDA8 ozone monthly variation in the Northeast, especially for spring and summer, with biases less than 5 ppb. The model, however, underestimates the summer MDA8 in Texas and the Southeast by more than 10 ppb. As compared with limited observations from CASTNET and IMPROVE, the model captures the key distribution features of annual mean concentrations of ammonium, nitrate, and sulfate aerosols, more realistic than a few global models. As compared with the NADP measurements, the model well reproduces the wet deposition of these aerosols in both spatial distribution and concentration levels. The simulated wet deposition of the aerosols is greater by one order of magnitude than the corresponding dry deposition. This implies that the wet removal process is the major sink of the aerosols. The modeled mercury wet deposition is also in reasonable agreement with the sparse NADP data in the Northeast and Midwest, but underestimated in the Southeast due to the missing sources from Mexico and oceans.
  • We have completed the CMAQ simulations for future full 5 years (2048-2052) under A1Fi and A1B scenarios with climate and/or emissions changes. We have found that the two scenarios project substantially different U.S. air quality changes. Below, we summarize the major findings in terms of future U.S. air quality changes from a regional air quality model perspective, focusing on the differences between the two scenarios and also the contributions of climate changes only as compared with both climate and emissions changes.
  • 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 improve 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. Compare 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 2100s. The projected trends of both surface air temperature and precipitation scatter more widely over all subdomains in 2100s as compared with 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 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 Northeast, but underestimated the wet deposition in Southeast, especially in Florida.
  • A series of sensitivity experiments based on CAM-Chem are designed to explore the relationship in changes of sulfate and nitrate aerosols. Sensitivity experiments include SOx emission reduced to: 10%; 20%; 50% of original emission 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 time, it is highly affected by SOx emissions due to a chemical competition mechanism. In winter time, 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 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 presence of clouds. The current mercury emission includes emissions from anthropogenic sources, soil sources, ocean, biofuel and volcano. The simulation on current atmospheric mercury pollution presents the right wet deposit pattern to the observation by national atmospheric deposition program. The time series comparison to observation on four stations also convinced 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) (IPCC2001). With the projected emissions, CAM-Chem is implemented to simulate the future mercury pollutions under each scenario. The largest increase of global mercury emission on 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 current concentration. The results under A1B scenario are a little bit lower. The increasing ratio is around two times more. Both emission and concentration changes under B1 scenario are the smallest; however, the concentrations are still nearly doubled based on current value. Although the emission over the U.S. region is 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 CAM-Chem. 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 PM 10 and PM 2.5 simulations.
  • We have completed the CMM5 integration driven by the CCSM3 for 1995-2005, and 2046-2055 under the IPCC B1, A1B and A1FI emissions scenarios. The CWRF integration driven by the CCSM3 for 1995-2005 was just finished. The result continues to support our earlier finding 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 completed the global CAM-Chem simulations driven by CCSM3 climate conditions and the regional CMAQ simulations driven by CMM5 climate conditions and CAM-Chem chemical lateral boundary conditions for the present (1998-2002) and future (2048-2052). These global and regional simulations are now being analyzed for the assessment of individual and combined effects of global climate and emissions change on U.S. air quality (ozone, PM, mercury).
  • We have demonstrated that the Bermuda high over the North Atlantic plays a central role on the U.S. climate and ozone distribution. We found that the Bermuda high variations in strength or east-west movement induces a distinct ozone oscillation between the Southern Plains-Midwest and eastern coastal States, and that this oscillation exhibits strong decadal variations that must be considered in the dynamic management of the U.S. air quality. Unfortunately, all existing GCMs poorly simulate the Bermuda high interannual correlation patterns, imposing a serious problem for U.S. air quality modeling.
  • We have investigated the effects of projected global changes in climate and human-related emissions on the potential risk of hazardous ozone pollution episodes using the CAM-Chem driven by the CCSM3 climate conditions under the A1FI, A1B and B1 scenarios. The projected changes in air temperature, precipitation, lighting, planetary boundary layer height and cyclone activities tend to intensify the associated extreme weather conditions that foster the risk of high ozone pollution episodes over many parts of the world. Under the A1B and B1 scenarios, the risk of hazardous ozone pollution episodes will likely decrease in developed countries, but increase in developing countries. Under the A1FI scenario, the hazardous risks are overall increase.
  • We have developed a mechanistic representation of the atmospheric mercury cycle and implemented it into the CAM-Chem to simulate the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg0), reactive mercury (HgII), and particulate mercury (HgP). The evaluation of simulated total gaseous mercury (TGM) concentrations with measurements from available worldwide sites and mercury wet depositions over the continental United States against observations at the Mercury Deposition Network stations indicates a strong capability for the CAM-Chem mercury mechanism to represent the atmospheric mercury cycle. Sensitivity experiments show that 22% of total mercury deposition and 25% of TGM concentrations in the United States result from domestic anthropogenic sources, but only 9% of total mercury deposition and 7% of TGM concentrations are contributed by transpacific transport. However, the contributions of domestic and transpacific sources on the western U.S. levels of mercury are comparable.
  • We investigate the effects of projected global changes in climate and human-related emissions for the year 2050 relative to 2000 for trends in the potential risk of hazardous ozone pollution episodes using a global climate chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry), driven by meteorology output from Community Climate System Model version 3. The projected changes in climate are likely to foster the risk of high ozone pollution episodes over many parts of the world. Our analysis under projected climate and emissions on the frequency of “hazardous ozone days“ in which the peak ozone concentration exceed the limit in the summer of 2050, based on 8 and 1-hour standards, show that the risk of hazardous ozone pollution episodes will likely increase in developing regions, but changes of risk in developed regions depend on scenarios. The relative change of high ozone days is relatively larger under the 1-hour standard thant 8-hour standard, which indicates the the changes of surface ozone level are more significantly presented on the high value part.
  • We investigate the relative contributions of changes in local anthropogenic emissions (LE) versus changes in remote anthropogenic emissions (RE) to global surface ozone air quality in 2050 through a global climate chemistry model CAM-Chem driven by the meteorology output from CCSM-3. We find that projected changes in anthropogenic emissions under the A1FI scenario lead to an increase of 5-14 ppb in summer time daily maximum 8-hour (DM8H) ozone concentration over the Unioted States by 2050, of which 48% is contributed by LE changes and 52% is contributed by RE changes. However, under the A1B and B1 scenarios, contributions from LE changes are much larger than that from RE changes over all three regions except the Asia under the B1 scenario, in which the RE changes contribute 31% of total change. The results indicate that for the United States and Europe, pollution control is a local issue under global low emission situations, while it becomes an international issue when fossil fuel use is rapidly increasing. Due to the weak Euro-Asia transport, local emission increase seems to be the main force for Asia’s ozone air quality change under all cases except the low emission scenario B1. Therefore, the strategies for regional air quality control need to be based on the global emissions perspective.
  • A mechanistic representation of the atmospheric mercury cycle is developed for CAM-Chem. The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg0), reactive mercury (HgII), and particulate mercury (HgP). The chemistry mechanism includes the oxidation of Hg0 in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg0. Simulated wet depositions of mercury over the continental United States are compared to observations on 26 Mercury Deposition Network stations to test the wet deposition simulations. Both the evaluations on gaseous concentration simulation and wet deposition simulation confirm the ability of the CAM-Chem mercury model in simulations of atmospheric mercury cycle. In addition, the simulated results also present the global mercury air quality, which indicate that mercury pollution in East Asia and Southern Africa is very serious with TGM concentrations above 3.0 ng/m3.
  • We have completed the evaluation of aerosol simulations from the CMM5-CMAQ model system for the present conditions (1995-1999). We found that the CMAQ simulations well captured the average ground-level PM2.5 (particulate matter with size smaller than 2.5 microns) concentrations in the rural/suburban sites, but had substantial underestimation in the urban areas, especially megacities such as Los Angeles. These results suggest that the modeling approach applied provides high credibility for the future projections of regional PM2.5 pollution, but higher spatial resolution is needed to resolve the emissions and meteorology in urban areas for better PM2.5 pollution simulations in the future. We also conducted present-day CMAQ simulations with the CAM-Chem lateral boundary conditions (LBCs), and results show lower PM2.5 ubiquitously over the United States, which suggests the CAM-Chem LBCs transport less air pollutants into the United States than the clean LBCs set default in the CMAQ model. The consequence of these present-day model behaviors on future U.S. air quality assessment will be addressed in the remaining period of this project.
  • We have completed the analysis of surface ozone simulations over the United States under different climate and emissions scenarios. The validation of current ozone prediction shows that the CMM5-CMAQ model system can capture the summertime ozone pollution. The individual effect of climate change, emission, and LBCs has been identified. We found that the uncertainty introduced through using LBCs is comparable the influence of climate change alone. The differences of ozone trend predicted by CAM-Chem and CMAQ indicate the importance of considering effects of LBCs on the future air quality.
  • We have completed the analysis on the PM2.5 simulations projected for the future conditions under different climate and emissions scenarios (A1Fi and A1B).  It is found that ground-level PM2.5 concentrations decrease in the eastern United States under both A1Fi and A1B scenarios; however the PM2.5 levels increase in the western United States under these scenarios. We also investigated the future projections with only climate change (emissions were kept as present-day level), and results suggest that the effects of climate change on ground-level PM2.5 pollution are one order of magnitude lower than the effects of emissions change.
  • We have actively participated in national and regional (Northeast United States and Chicago) assessments of climate change and air quality impacts. With the support of this EPA STAR project, published 18 papers, submitted 1 paper, and almost completed 2 manuscripts for publication in peer-reviewed journals. Among these, there were 1 published, 3 submitted, and 3 almost completed manuscripts during the last project year alone. While the abstracts for each of all manuscripts are given, this report only includes summary discussions of the key results from the 3 manuscripts to be submitted.
  • This EPA projects have supported studies of two graduate students at UIUC, Jin-Tai Lin (Ph.D. degree earned in 2008), and Hang Lei (Ph.D. degree earned in 2011). 


Journal Articles on this Report : 20 Displayed | Download in RIS Format

Other project views: All 20 publications 20 publications in selected types All 20 journal articles
Type Citation Project Document Sources
Journal Article Anderson BT, Hayhoe K, Liang X-Z. Anthropogenic-induced changes in twenty-first century summertime hydroclimatology of the Northeastern US. Climatic Change 2010;99(3-4):403-423. R833373 (Final)
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  • Journal Article 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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  • Journal Article 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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  • Journal Article 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. R833373 (Final)
    R835876 (2016)
    R835876 (2017)
    R835876 (2018)
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  • Journal Article Huang H-C, Lin JT, Tao Z, Choi H, Patten K, Kunkel K, Xu M, Zhu J, Liang X-Z, Williams A, Caughey M, Wuebbles DJ, Wang J. Impacts of long-range transport of global pollutants and precursor gases on U.S. air quality under future climatic conditions. Journal of Geophysical Research–Atmospheres 2008;113(D19):D19307 (15 pp.). R833373 (Final)
    R830963 (Final)
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  • Journal Article 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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  • Journal Article Lei H, Wuebbles DJ, Liang X-Z. Projected risk of high ozone episodes in 2050. Atmospheric Environment 2012;59:567-577. R833373 (Final)
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  • Journal Article Lei H, Wuebbles DJ, Liang X-Z, Olsen S. Domestic versus international contributions on 2050 ozone air quality: how much is convertible by regional control? Atmospheric Environment 2013;68:315-325. R833373 (Final)
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  • Journal Article Lei H, Liang X-Z, Wuebbles DJ, Tao Z. Model analyses of atmospheric mercury:present air quality and effects of transpacific transport on the United States. Atmospheric Chemistry and Physics 2013;13(21):10807-10825. R833373 (Final)
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  • Journal Article Lei H, Wuebbles DJ, Liang X-Z, Tao Z, Olsen S, Artz R, Ren X, Cohen M. Projections of atmospheric mercury levels and their effect on air quality in the United States. Atmospheric Chemistry and Physics 2014;14(2):783-795. R833373 (Final)
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  • Journal Article Liang X-Z, Kunkel KE, Meehl GA, Jones RG, Wang JXL. Regional climate models downscaling analysis of general circulation models present climate biases propagation into future change projections. Geophysical Research Letters 2008;35(8):L08709 (5 pp.). R833373 (Final)
    R830963 (Final)
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  • Journal Article Liang X-Z, Xu M, Yuan X, Ling T, Choi HI, Zhang F, Chen L, Liu S, Su S, Qiao F, He Y, Wang JXL, Kunkel KE, Gao W, Joseph E, Morris V, Yu T-W, Dudhia J, Michalakes J. Regional Climate–Weather Research and Forecasting model. Bulletin of the American Meteorological Society 2012;93(9):1363-1387. R833373 (Final)
    R834189 (2012)
    R834189 (2013)
    R834189 (Final)
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  • Journal Article Lin J-T, Wuebbles DJ, Huang H-C, Tao Z, Caughey M, Liang X-Z, Zhu J-H, Holloway T. Potential effects of climate and emissions changes on surface ozone in the Chicago area. Journal of Great Lakes Research 2010;36(Suppl 2):59-64. R833373 (Final)
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  • Journal Article Lin J-T, Wuebbles DJ, Liang X-Z. Effects of intercontinental transport on surface ozone over the United States:present and future assessment with a global model. Geophysical Research Letters 2008;35(2):L02805 (6 pp.). R833373 (Final)
    R830963 (Final)
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  • Journal Article Lin J-T, Youn D, Liang X-Z, Wuebbles DJ. Global model simulation of summertime U.S. ozone diurnal cycle and its sensitivity to PBL mixing, spatial resolution, and emissions. Atmospheric Environment 2008;42(36):8470-8483. R833373 (Final)
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  • Journal Article Markus M, Wuebbles DJ, Liang X-Z, Hayhoe K, Kristovich DAR. Diagnostic analysis of future climate scenarios applied to urban flooding in the Chicago metropolitan area. Climatic Change 2012;111(3-4):879-902. R833373 (2010)
    R833373 (Final)
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  • Journal Article Post ES, Grambsch A, Weaver C, Morefield P, Huang J, Leung LY, Nolte CG, Adams P, Liang XZ, Zhu JH, Mahoney H. Variation in estimated ozone-related health impacts of climate change due to modeling choices and assumptions. Environmental Health Perspectives 2012;120(11):1559-1564. R833373 (2011)
    R833373 (Final)
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  • Journal Article 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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  • Journal Article Weaver CP, Liang X-Z, Zhu J, Adams PJ, Amar P, Avise J, Caughey M, Chen J, Cohen RC, Cooter E, Dawson JP, Gilliam R, Gilliland A, Goldstein AH, Grambsch A, Grano D, Guenther A, Gustafson WI, Harley RA, He S, Hemming B, Hogrefe C, Huang H-C, Hunt SW, Jacob DJ, Kinney PL, Kunkel K, Lamarque J-F, Lamb B, Larkin NK, Leung LR, Liao K-J, Lin J-T, Lynn BH, Manomaiphiboon K, Mass C, McKenzie D, Mickley LJ, O'neill SM, Nolte C, Pandis SN, Racherla PN, Rosenzweig C, Russell AG, Salathe E, Steiner AL, Tagaris E, Tao Z, Tonse S, Wiedinmyer C, Williams A, Winner DA, Woo J-H, Wu S, Wuebbles DJ. A preliminary synthesis of modeled climate change impacts on U.S. regional ozone concentrations. Bulletin of the American Meteorological Society 2009;90(12):1843-1863. R833373 (Final)
    R830960 (Final)
    R830964 (Final)
    R833369 (Final)
    R833370 (Final)
    R833374 (Final)
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  • Journal Article Zhu J, Liang X-Z. Impacts of the Bermuda High on regional climate and air quality over the United States. Journal of Climate 2013;26(3):1018-1032. R833373 (Final)
    R834189 (Final)
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  • Supplemental Keywords:

    Climate change, emission, uncertainty, pollutant transport, ozone, particulate matter, mercury, aerosol, dust, deposition, regional climate model, air quality model, RFA, Air, climate change, Air Pollution Effects, Atmosphere, air quality modeling, environmental monitoring, particulate matter

    Relevant Websites:

    http://cwrf.umd.edu/application.php?aqm Exit

    Progress and Final Reports:

    Original Abstract
  • 2007 Progress Report
  • 2008 Progress Report
  • 2009 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report