Ozone and UV Studies Breakout Session Summary

DOE Atmospheric Chemistry Annual Meeting, Nov. 1996


Chaired by
Betsy Weatherhead and David Rusch


The DOE Ozone and UV Group is focused on improving our understanding of ozone and UV over mid-latitudes. Because ozone and UV have important human health and environmental impacts and because both ozone and UV are strongly impacted by anthropogenic emissions, careful and accurate assessment of these two environmental parameters is crucial for future energy decisions. Projects within this group focus on examining existing data, developing models which represent our present understanding, and developing instrumentation to be used in future investigations. In all projects, the highest level of accuracy and reliability are attempted.

Both ozone and UV are important issues in formulating the national energy policies, not solely, as was once thought, because of CFC production. Energy choices relating to greenhouse gas emissions can significantly affect the temperature and dynamics of the stratosphere and therefore can have direct impact on both ozone and UV. Because of the enormous costs attributed to UV damage, both economically and to the public health, energy decisions must incorporate accurate assessments of the impacts on ozone and UV levels at mid-latitudes. The ozone and UV groups within the Department of Energy's Atmospheric Chemistry Program has been working to assure that present assessment and attribution of changes in ozone and UV are properly understood. Many measurements of ozone and UV-B have been made by a variety of different groups both nationally and internationally. Further investigation shows that care must be taken in interpreting the results of these measurements. The DOE ACP ozone and UV group have closely examined the algorithms for interpreting existing data, the instrumentation and the cause for the observed changes. Both models and measurements have been used to interpret the observed changes and properly assess the causes.

The DOE Atmospheric Chemistry Group has included work on ozone and UV issues for three years. During this time the ozone and UV group has focused on six areas of significant importance to the DOE goals.

1. Stratospheric Dynamics and Chemistry. Both dynamics and chemistry strongly influence ozone, and therefore UV, levels at mid-latitudes. Because some of the changes occur on multi-year time scales, their assessment is necessary to determine the cause of observed changes.

2. Quality of Ozone Data. The quality of both column amounts and vertical profile of ozone must be assessed in order to determine if changes at mid-latitudes can be detected. Present data show discrepancies between data sets which must be understood.

3. Ozone Trends. Trends in ozone at mid-latitudes are crucial to determine the impact of anthropogenic influences to data. Reliable trends are important as is proper attribution of the observed trends.

4. Longtime Aerosol Variability. As aerosols are being recognized as a major factor in determining climate, their proper assessment is becoming important to energy planning decisions.

5. UV Modeling. As UV measurements are too costly and too difficult to perform in all areas of the world, UV modeling is necessary to estimate UV at any location and time. UV modeling is essential for assessing UV damage to the biosphere, and for understanding the impact of photo-oxidants on air quality.

6. UV Measurements. Prior analysis of UV data has been clouded with confusion and controversy. Proper assessment of long-term UV changes is necessary to make appropriate energy decisions.

While the ozone and UV group is rather new and it is recognized that research at this level often requires several years before major goals can be reached, nonetheless, significant advances have been noted at the Atmospheric Chemistry Program's Annual Meeting in November. 1996. While individual project summaries will be supplied elsewhere, here we will concentrate on the future directions of this group.

Future Directions

The group recognizes that the UV, ozone, and aerosol issues are closely connected physically and experimentally. Understanding the total picture is essential to charting the future of energy policy in the United States.

Ozone issues. The determination of ozone trends remain a key issue. It is necessary to extend the trend determinations with new and continuing data sets such as from UARS, SBUV, TOMS, and ground based data from lidar, Umhehr and balloons. In addition, new SAGE transmission data will be available in mid to late 1997. The identification and quantification of short term (less than days) ozone changes is also important to the full understanding of ozone. The intercomparison, clarification and qualification of the historical data base is a high priority. The development and improvement of algorithms for SAGE and ground based measurements is also needed.

New Applications of Satellite Data. There is much more information contained in the satellite ozone and aerosol data than is currently being exploited. Satellite data contains information on troposhperic ozone, aerosols in the upper troposphere and lower stratosphere, troposphere-stratosphere exchange, and global transport of pollutants.

Ozone and UV Modeling. There is a need to quantify the measured long-term ozone changes with respect to chemistry, dynamics, and radiation. The interaction of the UV-B/Ozone and the modeling groups, established at this meeting, is vital in this regard. Quantification of the amount of UV-B radiation reaching the ground has impacts on understanding tropospheric chemistry.

UV-B Trends. The effects of tropospheric ozone and aerosols on surface UV radiation are still poorly understood, and may have changed substantially since pre-industrial days. Evaluation and understanding of all available UV surface measurements is especially important in understanding UV-B trends, as is the development of new measurement techniques.

DOE Concerns. Ozone and UV radiation are sensitive to a number of energy-related emissions of greenhouse gases and tropospheric oxidant precursors. Strong coupling between the troposphere and stratosphere occurs via transport, chemical, and thermal mechanisms. The importance of these complex interactions is now well recognized, but many questions remain to be answered in order to provide a more sound scientific basis for future energy policy.