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2007 Progress Report: A Coupled Measurement-Modeling Approach to Improve Biogenic Emission Estimates: Application to Future Air Quality Assessments
EPA Grant Number: R831454Title: A Coupled Measurement-Modeling Approach to Improve Biogenic Emission Estimates: Application to Future Air Quality Assessments
Investigators: Mao, Huiting , Chen, Ming , Griffin, Robert J. , Sive, Barkley , Talbot, Robert , Varner, Ruth
Institution: University of New Hampshire - Main Campus
EPA Project Officer: Bloomer, Bryan
Project Period: January 1, 2004 through December 31, 2006
Project Period Covered by this Report: January 1, 2007 through December 31, 2008
Project Amount: $750,000
RFA: Consequences of Global Change for Air Quality: Spatial Patterns in Air Pollution Emissions (2003)
Research Category: Air Quality and Air Toxics , Global Climate Change
Description:
Objective:This investigation was focused on the northeastern U.S. with specific objectives to: (1) predict changes in regional climate that subsequently influence natural biogenic emissions and air quality, (2) quantify modifications in plant ecosystem composition due to changes in regional climate, (3) estimate regional biogenic emissions associated with a changing plant ecosystem and, (4) estimate aerosol loading, O3, NOx, hydrocarbons, and atmospheric oxidative capacity as a function of a changing regional climate and plant ecosystem. Our results quantify changes in the level of critical atmospheric species under future climate scenarios for 2050-2100, and provide a basis to assess their potential societal impacts on human health and key economic factors.
Progress Summary:Three successful field campaigns were conducted at the Duke Forest, NC, Forest- Atmosphere Carbon Transfer and Storage-I Research Facility (FACTS-I). A three week field campaign was conducted during September 2004 to measure volatile organic compounds (VOCs), oxygenated VOCs (OVOCs), O3, NO, CO2, organic and inorganic aerosols were conducted above the forest canopy under two CO2 environments: (1) present day (Plot 1, 370 ppmv) and (2) a future condition (Plot 2, 570 ppmv). This is the first time measurements of such a large suite of trace gases were conducted at the site. The second campaign lasted 10 days in June 2005 to quantify direct biogenic emissions of a suite of VOCs from vegetation in the two CO2 environments. The third campaign was measuring soil fluxes within Plots 1 and 2 on June 9, 2005, and September 20, 2005 in the two CO2 environments. We prioritized the analyses of measurements of CH3I, O3, carbonyl sulfide, vegetative and soil emissions of trace gases in the ambient and elevated CO2 environments to provide a comprehensive picture of diverse responses that the terrestrial system may have under increased CO2 levels. This is one aspect that is currently missing from future climate and air quality modeling research. Our data analysis work for Duke Forest and multi-year continuous data from UNH AIRMAP has identified that CH3I has a large natural terrestrial source strength comparable to its oceanic one. Measurements of soil-atmosphere exchange also revealed that high levels of reactive hydrocarbons are released from the soil/litter at Duke Forest, but the CO2- enriched environment exhibited suppressed soil fluxes of these compounds. Analyses of observations from the September 2004 campaign suggest that compared to the ambient CO2 environment, on average in the CO2 enriched Plot: 1.) isoprene mixing ratios were 8% higher, 2.) α-pinene and β-pinene mixing ratios were 22-24% lower, and 3.) O3 mixing ratios were increased by 6.5 ppbv. Box modeling results showed that the measured VOC species could account for 37% of the O3 increase in the elevated CO2 environment, implying the existence of unknown highly reactive VOCs. It appears that elevated CO2 levels can have opposing effects on biogenic emissions of reactive hydrocarbons, which in turn are linked closely to in situ O3 chemistry. Hence, our measurements suggest that it is a convoluted problem of how global warming accompanied by increased atmospheric CO2 may affect future O3 levels. More importantly, even with state-of-the-art instrumentation and modeling tools, it is likely that there is a large array of unknown but important highly reactive biogenic species. These need to be identified and their emissions and response to changes in ambient CO2 levels quantified. We investigated the impact of increased CO2 levels on carbonyl sulfide uptake by vegetation, which potentially can have significant influence on sulfate aerosol concentrations in the lower stratosphere, a potentially critical factor influencing the earthtropospheric climate system. We also found unusual enhancement in toluene levels during the warm season that may be attributed largely to biogenic emissions based on our measured ambient levels and flux measurements. This result will undoubtedly cause the community to reconsider application of the ratio of toluene/benzene as a marker for the photochemical age of an air mass. Preliminary results of the aerosol mass spectrometry measurements at Duke Forest suggest both anthropogenic and biogenic influences on secondary organic aerosol formation at the site. In the aspect of data analysis on climateair quality interaction, we identified the relationship between the occurrence of high O3 levels across the Northeast and large-scale circulation patterns (or map types) during the 2000 – 2004 time period. Our reconstruction of the O3 trend as a function of frequency and intensity associated with the top five primary map types captured 46% of that observed, a significant improvement compared to traditional methods. The map typing technique used in this study has proven to be a powerful tool that can be applied in the evaluation of regional climate and air quality modeling results. To complement the field measurements, our regional climate modeling system (RCMS) was used to simulate the Northeast environment for present and future climate conditions. Present day climate was reasonably reproduced, and under enhanced CO2 simulations showed warming at latitudes >40°N, weakened wintertime westerlies, and intensification of summer cyclonic circulations over the Northeast. Furthermore, a detailed analysis using NCEP reanalysis and EPA AIRNOW O3 data was performed for present day climate that illustrated a close tie between (meteorological) map types and summertime O3 distribution across the Northeast. We also studied two pollution episodes in summer 2004 using air quality modeling and observations from the UNH AIRMAP observing network (www.airmap.unh.edu) and the International Consortium for Atmospheric Research on Transport and Transformation (http://www.al.noaa.gov/ICARTT/ICARTTmain.shtml 
) field campaign. This included examination of chemical evolution in urban plumes leaving the northeastern U.S. and estimation of continental export of O3. Our results indicated that O3 formation over the ocean was significant, and it must be considered in future estimates of intercontinental transport. From our climate modeling work we found that precipitation in the future should become more episodic and convectively driven than in present day conditions, and with larger daily amounts. This implies an increased prevalence of drying and flooding conditions across the U.S. at the end of the 21st century. Furthermore, the present-day and future climate simulations coupled with a biographic model suggested that vegetation types would migrate systematically northward. The Caltech Atmospheric Chemistry Mechanism (CAACM) gas-phase chemistry model and The Model to Predict the Multi-phase Partitioning of Organics (MPMPO) have been interfaced with CMAQ to simulate O3 and particulate matter with a focus on secondary organic aerosols over the eastern U.S. during the period August 3-4, 2004. Unlike CMAQ with the built-in CB4/SORGAM modules, CMAQ with CACM/MPMPO can provide more information about the mechanisms of SOA formation. In terms of assessment of present and future air quality, we conducted five summer simulations over 2001-2005 using our RCMS and CMAQ. We analyzed the model output and evaluated the present-day results against continuous ground-based and ICARTT field campaign measurements. The reasonable agreement with observations gives us confidence in conducting a future regional quality assessment. Moreover, five four-month long seasonal runs using CMAQ have been conducted for present-day and future climate scenarios. Overall, we adhered to our proposed work schedule and made significant progress in understanding factors/processes shaping regional climate, biogenic emissions, and air quality to facilitate future climate and air quality assessments. Together our findings have important implications for future air quality and considerations for developing emission control regulations and policies.
Journal Articles on this Report: 5 Displayed | Download in RIS Format
| Other project views: | All 28 publications | 5 publications in selected types | All 5 journal articles |
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Chen J, Mao H, Talbot RW, Griffin RJ. Application of the CACM and MPMPO modules using the CMAQ model for the eastern United States. Journal of Geophysical Research 2006;111(D23S25), doi: 10.1029/2006JD007603. |
R831454 (2006) R831454 (2007) R831454 (Final) R831082 (2006) R831082 (2007) |
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Chen M, Mao H, Talbot R, Pollard D. Changes in precipitation characteristics over North America for doubled CO2. Geophysical Research Letters 2005;32:L19716, doi:10.1029/2005GL024535. |
R831454 (2007) R831454 (Final) |
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Hegarty J, Mao H, Talbot R. Synoptic controls on summertime surface on ozone in the northeastern United States. Journal of Geophysical Research 2007;112:D14306, doi:10.1029/2006JD008170. |
R831454 (2007) R831454 (Final) |
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Mao H, Talbot R, Troop D, Johnson R, Businger S, Thompson AM. Smart balloon observations over the North Atlantic: O3 data analysis and modeling. Journal of Geophysical Research 2006;111:D23S56, doi:10.1029/2005JD006507. |
R831454 (2006) R831454 (2007) R831454 (Final) |
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Sive BC, Varner RK, Mao H, Blake DR, Wingenter OW, Talbot R. A large terrestrial source of methyl iodide. Geophysical Research Letters 2007;34:L17808, doi:10.1029/2007GL030528. |
R831454 (2007) R831454 (Final) |
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vegetation type, NMHC’s, chemical transport, O3 precursors, EPA Region 1, Monitoring/Modeling, air sampling, biogenic ozone precursors, climate models, climate variability, climatic influence, ecological models,
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Ecosystem Protection/Environmental Exposure & Risk, Air, Scientific Discipline, RFA, Air Quality, Air Pollutants, climate change, Ecological Risk Assessment, Air Pollution Effects, Atmosphere, Atmospheric Sciences, particulate matter, Environmental Chemistry, Monitoring/Modeling, Environmental Monitoring, aerosols, meteorology, climate model, Global Climate Change, atmospheric models, airborne aerosols, BVOCs, ozone, atmospheric dispersion models, greenhouse gas, biogenic emission modeling, climatic influence, air quality models, climate models, aerosol formation, atmospheric chemistry, climate variability, environmental measurement, environmental stress, global change, atmospheric particulate matter, emissions monitoring, modeling, ambient air pollution, anthropogenic stress, atmospheric aerosol particles, ecological models, ambient aerosol, atmospheric transport, ecosystem models, greenhouse gases, air quality model
Progress and Final Reports:
2004 Progress Report
2005 Progress Report
2006 Progress Report
Original Abstract
Final Report