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 7, NUMBER 2, FEBRUARY 1994
- CLOUDS, AEROSOLS AND CLIMATE
the Dependence of Cloud Condensation Nucleus [CCN] Concentration
on Formation Rate," A.S. Ackerman (Dept. Atmos. Sci., AK-40,
Univ. Washington, Seattle WA 98195), O.B. Toon, P.V. Hobbs, Nature, 367(6462),
445-447, Feb. 3, 1994.
Previous work postulated that a bistable CCN concentration
regime could be established in marine stratocumulus, implying
that a small increase in CCN over the oceans could drastically
increase planetary albedo. Improved model calculations presented
here do not support this theory, but do indicate that high CCN
concentrations can persist in clouds advected to regimes of lower
CCN production rate.
Potential Role of the Ocean in Regulating Atmospheric
CH3Br," J.H. Butler, (CMDL, NOAA, 325 Broadway, Boulder CO
80303), Geophys. Res. Lett., 21(3), 185-188, Feb.
Uses a simple coupled atmosphere-ocean model to evaluate the
oceanic effect and its potential response to changes in
anthropogenic emissions of CH3Br. Finds an effective atmospheric
lifetime of 1.2 years.
Effects of Cloud Optical Thickness on Climate Warming," G.
Tselioudis (NASA Goddard Inst. Space Studies, 2880 Broadway, New
York NY 10025), A.A. Lacis et al., Nature, 366(6456),
670-672, Dec. 16, 1993.
Previous results from the International Satellite Cloud
Climatology Project have shown a relationship between low-cloud
optical thickness and cloud temperature that implies a positive
feedback between clouds and climate. This paper presents
calculations for a doubled CO2 climate using a 2-D
radiative-convective model, showing a latitudinal gradient in the
strength of this feedback that tends to eliminate the
high-latitude amplification of greenhouse warming predicted by
most climate models.
and Global Warming," O. Preining (Inst. Exper. Phys., Univ.
Vienna, Strudlhofgasse 4, 1090 Vienna, Austria), World Resour.
Rev., 5(4), 409-413, Dec. 1993.
Uses some simple calculations to demonstrate why aerosols must
be included properly in all climate models.
the Relationship Between Sulfate and Cloud Droplet Number
Concentrations," W.R. Leaitch (Cloud Phys. Res. Div., Atmos.
Environ. Serv., 4905 Dufferin St., Downsview ON M3H 5T4, Can.),
G.A. Isaac, J. Clim., 7(1), 206-212, Jan. 1994.
Compares observations of cloud droplet and cloud water sulfate
concentrations with the theoretical implications of modeling by
Kaufman et al. In terms of their prediction of the range of
possibilities for future climate, the data favor the possibility
of stronger cooling, but the uncertainty in modeling this process
is large and poorly constrained by the data.
Greenhouse Species in Clouds, Fogs and Aerosols," N.A.
Marley, J.S. Gaffney (Bldg. 203, Argonne Natl. Lab., Argonne IL
60439), M.M. Cunningham, Environ. Sci. Technol., 27(13),
2864-2869, Dec. 1993.
Describes measurements of water-soluble infrared absorbers
that can contribute to the long-wave radiation forcing of clouds,
fogs and aerosols, including sulfate, nitrate, formate, acetate,
oxalate, phenol, p-nitrophenol, ammonium, bicarbonate,
formaldehyde, methanol and ethanol. Discusses relative effects on
Latitudinal, and Secular Variations in Temperature Trend:
Evidence for Influence of Anthropogenic Sulfate," D.E.
Hunter (Scripps Inst. Oceanog., La Jolla CA 92093), S.E. Schwartz
et al. Geophys. Res. Lett., 20(22), 2455-2458, Nov.
Finds pronounced summer minima in the rate of temperature
increase in the Northern Hemisphere midlatitudes that are
consistent with the latitudinal distribution of anthropogenic
sulfate and changes in the rate of SO2 emissions over the
Empirical Analysis of the Strength of the
Phytoplankton-Dimethylsulfide-Cloud-Climate Feedback Cycle,"
M.G. Lawrence (M. Planck Inst. Chem., 55020 Mainz, Ger.), J.
Geophys. Res., 98(D11), 20,663-20,673, Nov. 20, 1993.
Develops an empirical model based on data relating the
individual components of this proposed feedback. Estimates that
the strength of the feedback is about 20% (10%-50%) of that
necessary to completely counteract a perturbation to the global
climate, such as that anticipated from greenhouse gases.
Contribution of Organic Aerosols to Cloud-Condensation-Nuclei
Concentrations," T. Novakov (Lawrence Berkeley Lab.,
Berkeley CA 94720), J.E. Penner, Nature, 365(6449),
823-826, Oct. 28, 1993.
Uses data from a marine site known to be affected by
anthropogenic emissions, to show that in such regions the role of
organic aerosols in determining the climatic effect of clouds may
be at least as important as that of sulfate aerosols.
from J. Geophys. Res., 98(D8), Aug. 20, 1993:
"Effect of Anthropogenic Sulfate Aerosols on Low-Level
Cloud Albedo over Oceans," Y. Kim (NASA Goddard Inst. Space
Studies, 2880 Broadway, New York NY 10025), R.D. Cess,
14,883-14,885. Satellite data demonstrate enhanced albedo off the
east coasts of North America and Asia where anthropogenic sulfate
is carried over the oceans. Similar trends are absent over ocean
regions of the Southern Hemisphere removed from sulfate sources.
"Light Scattering and Cloud Condensation Nucleus Activity
of Sulfate Aerosol Measured over the Northeast Atlantic
Ocean," D.A. Hegg (Dept. Atmos. Sci., AK-40, Univ.
Washington, Seattle WA 98195), R.J. Ferek, P.V. Hobbs,
14,887-14,894. Measurements suggest lower values for light
scattering coefficient and sulfate cloud condensation nucleus
efficiency than have been used in recent estimates of the
climatic impact of sulfate aerosols, and suggest an important
role for nonsulfate aerosol.
Processing of the Cloud Condensation Nucleus Spectrum and Its
Climatological Consequences," K.N. Bower (Dept. Phys., Univ.
Manchester Inst. Sci. & Technol., POB 88, Manchester M60 1QD,
UK), T.W. Choularton, Quart. J. Royal Meteor. Soc., 119(512),
655-679, July 1993 (Part A).
Presents a modeling study of the effects of aqueous phase
oxidation of sulfur by ozone and hydrogen peroxide. Although it
indicates significant modification of the cloud condensation
nucleus (CCN) spectrum emerging downwind of the processing cloud,
the effect is expected to be important only on local scales close
the source of new aerosol.
Years of Balloon-Borne Tropospheric Aerosol Measurements at
Laramie, Wyoming," D.J. Hoffmann (CMDL, NOAA, 325 Broadway,
Boulder CO 80303), J. Geophys. Res., 98(D7),
12,753-12,766, July 20, 1993.
A detailed examination of results from 265 high-altitude
balloon flights shows evidence of a decreasing trend of 1.6-1.8%
per year in the optically active tropospheric aerosol over the
past 20 years, which may be related to a similar reduction in
U.S. SO2 emissions.
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