New knowledge on the evolution of aerosols

Scientists have discovered how organic compounds behave in the atmosphere. The results were published in Science on 10 December 2009.

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It is still uncertain from the perspective of climate change research and forecasts how fine particles – also known as aerosols – behave in the atmosphere. Research findings published in Science on 10 December, introduce a “road map” describing the aging of organic aerosols as a result of oxidisation.

The road map will help improve the description of organic aerosols and their capacity to serve as nuclei in cloud droplets in air quality and climate models.

“Ultimately it is a question of how aerosols affect the climate and human health,” says Professor Markku Kulmala from the University of Helsinki Department of Physics. “Our contribution to the results published consisted of measurements carried out with an aerosol mass spectrometer and other aerosol instruments at the Hyytiälä Forestry Field Station.”

Tomi Raatikainen, a researcher from the Finnish Meteorological Institute, analysed the measurements and discovered that the organic matter in aerosols could be described with two components: one describing the new organic matter – in this case biogenic aerosol produced by forests – and the other describing aging organic matter. The latter has reached Hyytiälä from the densely populated areas of continental Europe.

According to the results, the organic age of the aerosols was linked with their capacity to form cloud droplets.

Organic compounds become similar in the atmosphere

The international group of 60 scientists has now determined what happens to organic compounds in the atmosphere. According to research, these compounds have a tendency to become similar in the atmosphere, regardless of what or where their source originally was. The differences in aerosol characteristics are evened out in the atmosphere in a matter of days. This knowledge helps to develop and improve climate models.

The research is based on aerosol mass spectrometer measurements around the world. The instrument was developed by FiDiPro Professor Douglas Worsnop, who is currently working at Kumpula campus in Helsinki.

The research involved six Finnish scientists from the universities of Helsinki and Kuopio and the Finnish Meteorological Institute.

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Text: Minna Meriläinen
Photo: Tapani Sainio

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