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Biogenic Emissions Characterization
Field measurements and modeling development to accurately estimate biogenic VOC emissions is the objective of this nationally coordinated program. Research is conducted in-house and in local forests. Work in this field is also coordinated with leading universities and other Federal agencies, including the National Center for Atmospheric Research (NCAR), the U. S. Forest Service, and ORD's National Exposure Research Laboratory (NERL). Biogenic emissions are VOC emissions found principally in forests and are the largest single source of VOCs in the U.S. This source is larger than all anthropogenic VOC emissions combined. Estimation of biogenic emissions is critical to assessing regional atmospheric chemistry processes causing tropospheric ozone. Research has shown that biogenic emissions produce NOx limited atmospheric chemistry over the entire Eastern U.S. region. The biogenic emissions model provides comprehensive biogenic VOC estimates for the U.S. and has been validated by field trials to demonstrate close agreement between the model's predictions and air quality measurements.
APPCD has been involved in research to improve algorithms used to estimate biogenic VOC and NOx emissions since 1990. Accurate estimates of emissions from biogenic sources (primarily soils and vegetation) are critical in formulating cost-effective anthropogenic pollution control strategies. This has been accomplished by performing modeling, measurement, and field and laboratory data analysis activities. Data and models developed during the course of this research are used by OAQPS in developing National Emissions Trends Database and Reports and by NERL in conducting regional air pollution simulations and in analysis of pollutant control strategy effectiveness. Research on emission factors, environmental controlling variables, and landscape data analysis are included in model development and validation efforts. Laboratory and field data are collected to improve chemical, plant species, temporal, and spatial resolution of emissions and to perform BEIS3 Model Validation studies. These studies enable us to establish uncertainty limits of model estimates.
Biogenic VOC emissions are thought to exceed anthropogenic VOC emissions on a national basis by up to a factor of two. In addition, many of these compounds, such as isoprene and methyl butenol, are highly reactive and control photochemistry in many locations. Model uncertainties range from ± 50% for summertime isoprene emission estimates (the most important compound emitted from U.S. deciduous forests) to over a factor of 10 for some oxygenated VOC such as hexenol.
In addition to those agencies listed above, collaborators in this research include the Washington State University Department of Civil and Environmental Engineering, the Wisconsin University Botany Department, the Duke University School of the Environment, and the University of California at Berkeley Department of Environmental Science, Policy, and Management.
The next version of the biogenic emission model will be available via a link from this site by Fall of 2002.