February 28, 2007
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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 4, NUMBER 12, DECEMBER 1991
"Long-Term Variations in Ultraviolet Sunlight Reaching the
Biosphere: Calculations for the Past Three Decades," J.E. Frederick (Dept.
Geophys. Sci., Univ. Chicago, 5734 S. Ellis Ave., Chicago IL 60637), E.C.
Weatherhead, E.K. Haywood, Photochem. Photobiol., 54(5),
781-788, Nov. 1991.
Applied radiative transfer calculations to a long-term database on
atmospheric ozone to determine the variability in UV that should have occurred
during 1957-1988 under clear, pollution-free skies. No significant trends span
the entire period, but for 1970-1988 the annually integrated irradiance
(weighted by the action spectrum for erythema) shows an upward trend of +2.1 +
or - 1.2% per decade for latitudes 40-52° N.
"Solar Ultraviolet Radiation in Southeast England: The Case for
Spectral Measurements," A.R. Webb (Dept. Meteor., Reading Univ., 2 Earley
Gate, Whiteknights, Reading RG6 2AU, England), ibid., 789-794.
Spectral measurements made since July 1989 show the daily and annual changes
in the UV-B part of the spectrum, and illustrate how the longer wavelengths
dominate when this part of the solar spectrum is incorporated in typical
broad-band measurements. At mid-high latitudes the UV irradiance at noon in
winter is less than that received at any time during the middle 12 hours of
daylight in summer. This should be acknowledged when assessing the consequences
of ozone depletion.
"Prolonged Enhancement in Surface Ultraviolet Radiation during the
Antarctic Spring of 1990," J.E. Frederick (Dept. Geophys. Sci., Univ.
Chicago, 5734 S. Ellis Ave., Chicago IL 60637), A.D. Alberts, Geophys. Res.
Lett., 18(10), 1869-1871, Oct. 1991.
Measurements at Palmer Station show that in the Austral spring of 1990,
enhanced UV irradiances at the surface persisted well into December, several
weeks later than in the previous two years. Peak values were about double those
expected at summer solstice with an unperturbed ozone column.
"A Relationship for the Penetration of Ultraviolet B
Radiation into the Norwegian Sea," N.K. Hjerslev (Geophys. Inst., Univ.
Copenhagen, Haraldsgade 6, DK-2200 Copenhagen-N, Den.), J. Geophys. Res.,
96(C9), 17,003-17,005, Sep. 15, 1991. Obtained a linear relation between
the vertical attenuation of UV-B and blue irradiance; the 1% depth of UV-B
irradiance in this region is 23-33 m deeper than in surrounding waters.
"Spectral Measurements of Global and Diffuse Solar Ultraviolet-B
Radiant Exposure and Ozone Variations," M. Blumthaler (Inst. Medical Phys.,
Univ. Innsbruck, Muellerstr. 44, A-6020 Innsbruck, Austria), W. Ambach, Photochem.
Photobiol., 54(3), 429-432, Sep. 1991. Discusses technical details
of measurements taken since 1985 in the Swiss Alps.
"Absorption Coefficients of Ice from 150 to 400 nm," D.K.
Perovich (Cold Regions Res. Lab., U.S. Army, 72 Lyme Rd., Hanover NH 03755),
J.W. Govoni, Geophys. Res. Lett., 18(7), 1233-1235, July 1991.
Absorption coefficients for pure bubble-free ice are crucial for theoretically
determining levels of UV radiation reaching marine biota under sea ice.
Laboratory measurements on a block of ice show that existing data on the
interaction of visible light with snow and sea ice will provide a first-order
estimate of UV optical properties.
"The Ultraviolet Radiation Environment of the Ant-arctic Peninsula:
The Roles of Ozone and Cloud Cover," D. Lubin (MC A-021, Space Inst.,
Scripps Inst. Oceanog., Univ. Calif., La Jolla CA 92093), J.E. Frederick, J.
Appl. Meteor., 30(4), 478-493, Apr. 1991.
Hourly measurements from a ground-based scanning spectroradiometer and
radiative transfer modeling show that, in a seasonally averaged sense,
cloudiness has no effect on the percentage of enhancement in UV-B irradiance
that results from the springtime ozone depletion. Over shorter periods,
increased cloud cover can produce a surface UV-B level comparable to that found
under an unperturbed ozone column and clear skies.
Two articles from Geophys. Res. Lett., 17(12), Nov. 1990.
"Enhanced Ultraviolet Transmission of Antarctic Sea Ice during the
Austral Spring," H.J. Trodahl (Dept. Phys., Victoria Univ., POB 600,
Wellington, New Zealand), R.G. Buckley, 2177-2179. The first of such
measurements indicate that transmission is largest in the spring, so that life
under the ice experiences its largest UV dose in October. Dose enhancements by
as much as an order of magnitude will have been experienced under the ozone
holes of recent years.
"Biologically Effective Ultraviolet Radiation, Total Ozone Abundance,
and Cloud Optical Depth at McMurdo Station, Antarctica, Sep. 15, 1988, through
Apr. 15, 1989," K. Stamnes (Geophys. Inst., Univ. Alaska, Fairbanks AK
99775), J. Slusser et al., 2181-2184. Spectral measurements taken at the surface
show a general enhancement of about 20% in biologically effective UV dose in
October 1988, compared to March 1989. The percent decrease in ozone abundance is
about 2.5, in agreement with theoretical predictions. No spring/fall asymmetry
in cloudiness as it affects the surface UV budget is discernible.
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