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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 5, NUMBER 3, MARCH 1992

PROFESSIONAL PUBLICATIONS...
ULTRAVIOLET MEASUREMENT

Item #d92mar36

"Ultraviolet Radiation Received in Antarctica in Comparison with the Indian Region," M.C. Sharma (Nat. Phys. Lab., Krishnan Rd., New Delhi 110012, India), B.N. Srivastava, Atmos. Environ., 26A(4), 731-734, 1992.

Calculates UV-B reaching the ground for a range of total ozone contents (100-340 DU) at several zenith angles appropriate to Indian as well as Antarctic stations. The radiation received at Antarctica under the ozone hole is comparable to that received at equatorial stations in summer.

Item #d92mar37

"Enhancement of Atmospheric Radiation by an Aerosol Layer," D.V. Michelangeli (Div. Geol. Sci., California Inst. Technol., Pasadena CA 91125), M. Allen et al., J. Geophys. Res., 97(D1), 865-874, Jan. 20, 1992.

A stratospheric haze layer can produce increases in both the actinic flux and the irradiance below the layer, as a consequence of "photon trapping." Calculations with a new radiative transfer model show that one consequence of the El Chichón eruption was an increase in the midday surface actinic flux at 20° N in summer by as much as 45% at 2900 Å. This increase in the UV-B range was caused entirely by aerosol scattering, without any reduction in the ozone column.

Item #d92mar38

"Implications of Recent Total Atmospheric Ozone Measurements for Biologically Active Ultraviolet Radiation Reaching the Earth's Surface," S. Madronich (NCAR, POB 3000, Boulder CO 80307), Geophys. Res. Lett., 19(1), 37-40, Jan. 3, 1992.

The changes in biologically active UV reaching the Earth's surface from 1979 to 1989 were calculated from recent satellite measurements of total ozone. The increases are substantially larger than previous estimates, especially at middle and high latitudes of both hemispheres. Some uncertainties do exist, particularly with regard to possible long-term changes in cloud cover; direct measurements are needed.

Item #d92mar39

Two items from ibid., 18(12), Dec. 1991:

"Effect of Anthropogenic Aerosols on Biologically Active Ultraviolet Radiation," S.C. Liu (Aeronomy Lab., NOAA, 325 Broadway, Boulder CO 80303), S.A. McKeen, S. Madronich, 2265-2268.

Calculations based on observed values of visual range show that in nonurban areas of the industrialized countries the amount of UV-B reaching the surface has decreased by 5-18% since the industrial revolution, mainly due to scattering by aerosols formed from SO2 emissions. This effect may have partly or fully offset UV-B increases from stratospheric ozone depletion, but any offset will be limited as SO2 emissions level off in the industrialized countries.

"The Relationship between Erythemal UV and Ozone, Derived from Spectral Irradiance Measurements," R.L. McKenzie (DSIR Phys. Sci., Lauder, Central Otago 9182, New Zealand), W.A. Matthews, P.V. Johnston, 2269-2272.

Investigated the relative importance of solar zenith angle, ozone and cloud cover to erythemally active UV using ground-based UV measurements from Lauder, New Zealand. At this site zenith angle is dominant, but clouds frequently attenuate the clear sky irradiances by more than 50%. Ozone reductions of 1% typically increase active UV by 1.25%.

Item #d92mar40

"Long-Term Variation of Solar UV-B (290-330 nm) Observed at the Earth's Surface," R.P. Kane (Inst. Pesquisas Espaciais, CP 515 BR-12201 Sao Jose Campos, SP, Brazil), Pure Appl. Geophys., 136(2-3), 201-210, 1991.

Estimates the individual influences on UV-B of solar irradiance variations, the quasi-biennial oscillation of stratospheric ozone, cloudiness and the El Chichón aerosol, over the last decade and a half. Compares results to measurements made at three U.S. locations and Jungfraujoch in the Swiss Alps. A lack of consistent results leads the author to suspect some source of error in the measurements that requires scrutiny.