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Title:
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AEROSOL; cycle and influence on the radiation balance ; MEMORA: MEasurement and MOdeling of the reduction of Radiation by Aerosol : cluster project in the National Research Programme on Global Air Pollution and Climate Change nr. 951205: report on Phase 1: 1996-1997
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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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1-8-1998
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ECN report number:
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Document type:
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ECN-R--98-015
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Other
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Number of pages:
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Full text:
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48
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Download PDF
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Abstract:
Anthropogenic aerosols reflect solar radiation and therefore act as acooling agent. The perturbation ('forcing') of the radiation balance is so
large that, according to estimates by IPCC, it could off-set the longwave
radiative forcing by the manmade greenhouse gases in areas like Europe. IPCC
reports that the uncertainty in the globally averaged aerosol forcing is of
the order of 3 W m"-2. This uncertainty exceeds the magnitude of the
longwave forcing by the manmade greenhouse gases. Of national interest is the
fact that the aerosol forcing is a local/regional phenomenon because of the
limited residence time of aerosols in the atmosphere. The claim by IPCC that
sulfate is the only relevant manmade aerosol component is highly questionable
for Europe. Whereas the value of the aerosol effect is so uncertain,
predictions of the coming trend are even more problematic. This is due to the
fact that the most important anthropogenic ingredients of the aerosol are not
directly emitted, but made in the atmosphere. A one to one relation between
emission of the precursors and resulting aerosol seems rather unlikely given
a non-linear historical trend. Therefore only a combined approach in which
aerosol fields are modeled and modeled fields together with the calculated
reduction in solar flux should be tested against measurements. This approach
should provide the tools to perform, with sufficient confidence, scenario
calculation for the aerosol effect. Improvement of the current large
uncertainty in the forcing of the radiation balance by anthropogenic aerosol
(in Europe) by a combined experimental modeling program. This is achieved by
assessment of the major aerosol components involved and their sources, using
detailed measurements in The Netherlands as a reference for model input and
output. 36 refs.
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