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Title:
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Antropogene aerosolen en de stralingsbalans van de aarde: antropogene"stof"deeltjes compenseren het versterkte broeikaseffect in Europa [ECN-I--
96-058]
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Author(s):
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Published by:
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Publication date:
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ECN
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1996
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ECN report number:
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Document type:
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ECN-I--96-058
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Other
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Number of pages:
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Full text:
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21
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Download PDF
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Abstract:
The local direct radiative forcing by manmade aerosols was assessed bymeans of extrapolation of 'column closure' experiments. In such tests the
amount of solar light reflected by the aerosol can be assigned to the various
anthropogenic aerosol components. Aerosol-nitrate was more important than
aerosol-sulfate for the reflection. Strong indications were found that
'organic' material contributes to a similar degree to the forcing as the two
mentioned compounds. By combining extrapolations of the results in the
test-campaign with continuous monitoring of the aerosol light-scattering a
value for the average local radiative forcing was obtained of -2 W.m"-2. An
estimate of the regional indirect aerosol radiative forcing was made on the
basis of results of a study in a (large) cloud chamber. The number of cloud
droplets formed on aerosols in 'polluted' marine air was compared to the
number formed in the 'cleanest' marine air. The extra number of droplets was
translated to extra cloud reflectivity in the usual way and a value of -5
W.m"-2 was found for the forcing. This value is so high because of
persistent southwesterly 'polluted' marine air flows in The Netherlands. lt
is concluded that the cooling by manmade aerosol in the Netherlands and
vicinity is much larger than the local radiative warming by the enhanced
greenhouse gases. Ongoing follow-up experimental and modeling research should
quantify these first results. 3 figs., 7 refs.
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