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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics</journal_title>
		<journal_url>www.atmos-chem-phys.net</journal_url>
		<issn>1680-7316</issn>
		<eissn>1680-7324</eissn>
		<volume_number>10</volume_number>
		<issue_number>4</issue_number>
		<publication_year>2010</publication_year>
	</journal>
	<doi>10.5194/acp-10-1885-2010</doi>
	<article_url>http://www.atmos-chem-phys.net/10/1885/2010/</article_url>
	<abstract_html>http://www.atmos-chem-phys.net/10/1885/2010/acp-10-1885-2010.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys.net/10/1885/2010/acp-10-1885-2010.pdf</fulltext_pdf>
	<start_page>1885</start_page>
	<end_page>1898</end_page>
	<publication_date>2010-02-18</publication_date>
	<article_title content_type="html">Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>M. Kulmala</name>
			<email>markku.kulmala@helsinki.fi</email>
		</author>
		<author numeration="2" affiliations="1,2">
			<name>I. Riipinen</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>T. Nieminen</name>
		</author>
		<author numeration="4" affiliations="1">
			<name>M. Hulkkonen</name>
		</author>
		<author numeration="5" affiliations="1,3">
			<name>L. Sogacheva</name>
		</author>
		<author numeration="6" affiliations="1">
			<name>H. E. Manninen</name>
		</author>
		<author numeration="7" affiliations="1">
			<name>P. Paasonen</name>
		</author>
		<author numeration="8" affiliations="1">
			<name>T. Petäjä</name>
		</author>
		<author numeration="9" affiliations="1">
			<name>M. Dal Maso</name>
		</author>
		<author numeration="10" affiliations="1">
			<name>P. P. Aalto</name>
		</author>
		<author numeration="11" affiliations="3">
			<name>A. Viljanen</name>
		</author>
		<author numeration="12" affiliations="4">
			<name>I. Usoskin</name>
		</author>
		<author numeration="13" affiliations="1">
			<name>R. Vainio</name>
		</author>
		<author numeration="14" affiliations="5">
			<name>S. Mirme</name>
		</author>
		<author numeration="15" affiliations="5">
			<name>A. Mirme</name>
		</author>
		<author numeration="16" affiliations="6">
			<name>A. Minikin</name>
		</author>
		<author numeration="17" affiliations="6">
			<name>A. Petzold</name>
		</author>
		<author numeration="18" affiliations="5">
			<name>U. Hõrrak</name>
		</author>
		<author numeration="19" affiliations="7">
			<name>C. Plaß-Dülmer</name>
		</author>
		<author numeration="20" affiliations="8">
			<name>W. Birmili</name>
		</author>
		<author numeration="21" affiliations="3">
			<name>V.-M. Kerminen</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">University of Helsinki, Helsinki, Finland</affiliation>
		<affiliation numeration="2" content_type="html">Carnegie Mellon University, Pittsburgh, Pennsylvania, USA</affiliation>
		<affiliation numeration="3" content_type="html">Finnish Meteorological Institute, Helsinki, Finland</affiliation>
		<affiliation numeration="4" content_type="html">Sodankylä Geophysical Observatory (Oulu Unit), University of Oulu, Sodankylä, Finland</affiliation>
		<affiliation numeration="5" content_type="html">University of Tartu, Tartu, Estonia</affiliation>
		<affiliation numeration="6" content_type="html">Deutsches Zentrum für Luft- und Raumfahrt (DLR), Wessling, Germany</affiliation>
		<affiliation numeration="7" content_type="html">Meteorologisches Observatorium Hohenpeissenberg, Deutscher Wetterdienst (DWD), Hohenpeissenberg, Germany</affiliation>
		<affiliation numeration="8" content_type="html">Leibniz Institute for Tropospheric Research, Leipzig, German</affiliation>
	</affiliations>
	<abstract content_type="html">Aerosol particles affect the Earth&apos;s radiative balance by directly
scattering and absorbing solar radiation and, indirectly, through their
activation into cloud droplets. Both effects are known with considerable
uncertainty only, and translate into even bigger uncertainties in future
climate predictions. More than a decade ago, variations in galactic cosmic
rays were suggested to closely correlate with variations in atmospheric
cloud cover and therefore constitute a driving force behind
aerosol-cloud-climate interactions. Later, the enhancement of atmospheric
aerosol particle formation by ions generated from cosmic rays was proposed
as a physical mechanism explaining this correlation. Here, we report unique
observations on atmospheric aerosol formation based on measurements at the
SMEAR II station, Finland, over a solar cycle (years 1996–2008) that shed
new light on these presumed relationships. Our analysis shows that none of
the quantities related to aerosol formation correlates with the cosmic
ray-induced ionisation intensity (CRII). We also examined the contribution
of ions to new particle formation on the basis of novel ground-based and
airborne observations. A consistent result is that ion-induced formation
contributes typically significantly less than 10% to the number of new
particles, which would explain the missing correlation between CRII and
aerosol formation. Our main conclusion is that galactic cosmic rays appear
to play a minor role for atmospheric aerosol formation events, and so for the
connected aerosol-climate effects as well.</abstract>
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</article>

