February 28, 2007
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A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 5, NUMBER 3, MARCH 1992
"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),
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.
"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.
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.
"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.
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%.
"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),
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.
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