ECN publication
Antropogene aerosolen en de stralingsbalans van de aarde: antropogene"stof"deeltjes compenseren het versterkte broeikaseffect in Europa [ECN-I-- 96-058]
Published by: Publication date:
ECN 1996
ECN report number: Document type:
ECN-I--96-058 Other
Number of pages: Full text:
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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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