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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 9, NUMBER 1, JANUARY 1996

PROFESSIONAL PUBLICATIONS...
OZONE DEPLETION: UV MEASUREMENT

Item #d96jan18

Two related items in Nature, 377(6551), Oct. 26, 1995:

"The Radiation Equation," S. Madronich (Atmos. Chem. Div., NCAR, POB 3000, Boulder CO 80307), 682-683. Discusses the results of the next paper. Perhaps the biggest uncertainty in the study concerns the validity of extrapolating past ozone trends into the next century—an issue that has as much to do with humankind's ability to restrain its growing influence on atmospheric composition as it does with atmospheric processes.

"Effects of Clouds and Stratospheric Ozone Depletion on Ultraviolet Radiation Trends," D. Lubin (Calif. Space Inst., Univ. California, La Jolla CA 92093), E.H. Jensen, 710-713. Uses global satellite measurements of cloud reflectance to estimate the potentially large natural variability in UV radiation resulting from variations in cloud opacity. Compares this UV variability with trends in UV radiation calculated to accompany observed trends in total ozone abundance. By the end of this century, throughout many temperate regions, trends in summer average local-noon UV radiation dose rates relevant to mammalian skin cancer or plant damage will be significant compared to cloud variability. At some locations, this is already true.

Item #d96jan19

"Trends and Interannual Variations in Erythemal Sunlight, 1978-1993," J.E. Frederick (Dept. Geophys. Sci., Univ. Chicago, 5734 S. Ellis Ave., Chicago IL 60637), C. Erlick, Photochem. & Photobiol., 62(3), 476-484, Sep. 1995.

Attempts to define the long-term variability in solar UV irradiance received by selected regions of the Earth by incorporating the effects of cloudiness into estimates of UV irradiance, using a combination of measurements and numerical models. Although the general decline in ozone amounts over the period acted to increase erythemal (biologically active) irradiance, the changes tend to be obscured by the erratic variability associated with cloudiness, effectively widening the error bars for any estimate of trend. Over a period of 10-15 years it is questionable whether ground-based data sets will be able to establish the existence of a nonzero trend in erythemal irradiance at the 95% confidence level. A more detailed statistical analysis of this issue is warranted.

Item #d96jan20

"Increased UV Exposure in Finland in 1993," K. Jokela (Ctr. Radiation & Nuclear Safety, POB 14, FIN-00881 Helsinki, Finland), K. Leszczynski et al., ibid., 62(1), 101-107, July 1995.

Evaluates the UV exposure to the Finnish population during the period of exceptionally low ozone in April-May 1993, using measurements and theoretical calculations. Compared to periods of average ozone level, the erythemal UV falling onto horizontal surfaces on clear days increased 10% on average, with a maximum increase of 34%.