Testimony of

William Pendergrass

Physical Scientist

National Oceanic and Atmospheric Administration

U.S. Department of Commerce

before the

Great Smoky Mountains Congressional Caucus

October 19, 1999

Mr. Chairman, and members of the Great Smoky Mountains Congressional Caucus, my name is William Pendergrass, and I am a physical scientist at the National Oceanic and Atmospheric Administration's Atmospheric Turbulence and Diffusion Division in Oak Ridge, Tennessee. I want to thank you for the opportunity to testify today on NOAA's East Tennessee Ozone Study (ETOS). ETOS is an experimental program designed to measure and forecast ozone concentrations in the East Tennessee Valley region. NOAA's Atmospheric Turbulence and Diffusion Division (ATDD) initiated this measurement and forecasting program because of the potential for significant impacts on the East Tennessee Valley and Great Smoky Mountain National Park from elevated ozone levels. The goal of the program is to develop an air-quality forecasting system for East Tennessee.

The summer of 1998 produced interesting headlines in the local Knoxville press. Headlines ranged from "Air Quality at Clingman's Dome Hits Danger Level" to "Smoky's Air Quality Setting Worst Records." In 1998, the Great Smoky Mountain National Park reported 44 days of unhealthy ozone conditions; in 1999, the number of days increased to 51. While elevated ozone readings during the summer of 1998 had a significant impact on the Great Smoky Mountains, the high readings within the nearby East Tennessee Valley raised concerns about the potential economic and societal impacts of the U.S. Environmental Protection Agency's (EPA) new ozone standard, which is an 8-hour standard set at 0.08 parts per million that was recently remanded by the Court of Appeals for the D.C. Circuit, as contrasted with the old standard of 0.12 parts per million.

[Exhibit 1] NOAA initiated this study in collaboration with The University of Tennessee and the National Park Service. This community partnership has grown to include the State of Tennessee Department of Environment and Conservation, Knox County Air Quality Department, Chattanooga/Hamilton County Air Pollution Control, Tusculum College, University of Tennessee - Chattanooga, and East Tennessee State University. Recently, the Tennessee Valley Authority joined the collaborative effort. Representatives from the Western North Carolina Regional Air Pollution Control Agency and North Carolina's Department of Environment and Natural Resources have also attended various planning and data analysis workshops.

The ultimate goal of ETOS is the development of a validated air quality forecasting tool for East Tennessee which would also serve as a prototype for future NOAA air-quality models. [Exhibit 2]Ozone in the lower levels of the atmosphere is formed through a complex set of chemical reactions between two primary compounds: oxides of nitrogen (NOx), which result from man-made emissions from industrial and transportation activities; and, volatile organic compounds (VOCs), which are produced from various industrial processes, as well as emitted naturally by vegetation. NOAA's Health of the Atmosphere Program has identified that "natural emission of VOCs (from vegetation) are much greater than human produced emissions of these compounds in almost all areas of the southeastern U.S. studied by NOAA." This could have a significant impact on managing ozone through various control or reduction strategies, as reliance on VOC reductions may not be fully successful in reducing ozone concentrations in the southeastern United States.

[Exhibit 3] Equally important, if not more, is the ozone transported from surrounding regions into East Tennessee by winds aloft. The EPA's Ozone Transport Assessment Group suggests that ozone may be transported as much as 300 to 500 miles from its origin. NOAA's Health of the Atmosphere Program has found that the redistribution of ozone pollution which occurs at night plays a major role in transporting urban ozone into rural areas. [Exhibit 4] An example of the need to include transport winds in the ETOS study can be found with analysis of ozone exceedances in the Great Smoky Mountain National Park early this year. National Weather Service data and models run by ATDD show that the path by which the early May air mass reached the Great Smoky Mountain National Park was far from simple. Note that over the 48-hour period, the air mass crossed six states on its way to the Great Smoky Mountain National Park. Exhibit 4 also shows the locations of the industrial NOx emission sources in the region, extracted from EPA databases, scaled by the amount of their annual NOx emissions.

For East Tennessee, the challenge is to develop a model which recognizes the unique topography and climate of the region and that also incorporates the various chemical reactions and transport issues related to ozone formation. The complexity of the terrain within the East Tennessee Valley makes siting of both meteorological and ozone monitoring locations challenging. One solution led to a cooperative arrangement with the Tennessee Forest Service to use regional Forest Service fire watch towers as monitoring platforms. These sites provided excellent research platforms; and, in turn, meteorological data have been provided to various regional Forest Service offices for the summer and fall fire seasons.

[Exhibit 5] Analysis of ETOS '99 data has just begun. I would like to present several examples of measurements from this summer's program. During two intensive studies this summer additional ozone measurements were taken, using a variety of research aircraft. This exhibit represents two passes over the East Tennessee Valley with NOAA's Twin Otter research aircraft on July 27th. The observations are grouped according to EPA defined air quality scales: "moderate"; "unhealthy for sensitive groups"; "unhealthy"; and, "very unhealthy." During these aircraft measurements, the flight level varied between 1000 and 1500 feet, with sampling time extending from approximately noon into the early afternoon. Measurements indicate ozone values above 0.08 parts per million, the EPA's eight-hour standard which was recently remanded by the Court of Appeals for the D.C. Circuit, across the valley, with a notable increase downwind of the City of Knoxville. It should also be noted that readings which exceed the EPA standard were observed some distance upwind of the urbanized area of Knoxville, Tennessee, and other significant regional NOx emission sources. It is logical to attribute these upwind values to transport from outside the East Tennessee region.

[Exhibit 6] Using National Weather Service data and ATDD's models, a series of backward trajectories was calculated every six hours for the period July 25 through July 28. These trajectories identify the path over the previous 48 hours of the air mass which moved over East Tennessee on July 27th. As before, the figure also shows the major industrial NOx emission sources, as indicated by EPA databases. For these four days in late July 1999, the source region for the air transported into East Tennessee was the Ohio Valley.

We have accomplished the goals identified for ETOS '99. Current planning for next year's study anticipates that ETOS 2000 will be used as a validation/demonstration project. ETOS 2000 will expand its regional coverage to the eastern portion of the Great Smoky Mountain National Park, including the Asheville, North Carolina metropolitan area. Measurements conducted during ETOS 2000 will also expand to include natural VOCs. Regional coverage will extends outside the East Tennessee Valley to document regional background ozone concentrations in surrounding states.

[Exhibit 7] As demonstrated, the issue of ozone formation and air-quality forecasting is both complex and regional. The partitioning of the relative contributions of ozone transported into East Tennessee and ozone produced from local and regional industrial and transportation activities needs to be identified. [Exhibit 8] As indicated in exhibit 8, observations from the summer of 1999 indicate that the East Tennessee region does not meet a 0.08 parts per million ozone standard. As policy makers address air-quality issues, the ability to accurately forecast air quality offers many alternative control strategies. The knowledge obtained from ETOS will allow policy makers to evaluate model predictions for various emission control strategies. As NOAA expands its air quality forecasting capability, ETOS and its measurement base will provide a regional research and test bed for operational air quality forecasting tools for the future.

NOAA is committed to providing predictions and scientific understanding about our environment to improve our service to the public. My testimony today has provided only a snapshot of the ETOS program. Mr. Chairman, if you, or any other Member of the Great Smoky Mountains Congressional Caucus would like to explore the details of this program further, I would invite you to visit our laboratory in Oak Ridge, Tennessee.

Thank you, once again, for inviting NOAA to participate in today's hearing. This concludes my testimony, and I would be happy to answer any question you may have.