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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics Discussions</journal_title>
		<journal_url>www.atmos-chem-phys-discuss.net</journal_url>
		<issn>1680-7367</issn>
		<eissn>1680-7375</eissn>
		<volume_number>8</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2008</publication_year>
	</journal>
	<doi>10.5194/acpd-8-521-2008</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/8/521/2008/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/8/521/2008/acpd-8-521-2008.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/8/521/2008/acpd-8-521-2008.pdf</fulltext_pdf>
	<start_page>521</start_page>
	<end_page>548</end_page>
	<publication_date>2008-01-10</publication_date>
	<article_title content_type="html">Weekly patterns of aerosol in the United States</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>D. M. Murphy</name>
		</author>
		<author numeration="2" affiliations="1,2,5">
			<name>S. L. Capps</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>J. S. Daniel</name>
		</author>
		<author numeration="4" affiliations="1,3">
			<name>G. J. Frost</name>
		</author>
		<author numeration="5" affiliations="4">
			<name>W. H. White</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA</affiliation>
		<affiliation numeration="2" content_type="html">Vanderbilt University, Nashville, TN 37240, USA</affiliation>
		<affiliation numeration="3" content_type="html">Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA</affiliation>
		<affiliation numeration="4" content_type="html">Crocker Nuclear Laboratory, University of California, Davis, Davis, CA 95616, USA</affiliation>
		<affiliation numeration="5" content_type="html">now at: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA</affiliation>
	</affiliations>
	<abstract content_type="html">Data from the Interagency Monitoring of Protected Visual Environments
(IMPROVE) network of aerosol samplers and NOAA monitoring sites are examined
for weekly cycles. Fine particle elemental carbon, crustal elements, and
coarse particle mass had pronounced (up to 20%) weekly cycles with minima
on Sunday or Monday. Fine particle organic carbon and mass had smaller
amplitude cycles, also with Sunday or Monday minima. There was no
statistically significant weekly cycle in fine particle sulfate despite a 10
to 15% weekly cycle in power plant SO&lt;sub&gt;2&lt;/sub&gt; emissions. Although results
for nitrate must be treated with caution, it showed a pronounced weekly
cycle with an amplitude similar to elemental carbon. The only species found
with a weekend maximum was Pb, probably from general aviation on weekends.
Aerosol optical properties at NOAA monitoring sites were consistent with the
IMPROVE chemical data, with significant weekly cycles in aerosol light
absorption but not light scattering. These results support a large role of
diesel emissions in elemental carbon aerosol over the entire United States
and suggest that a large fraction of the airborne soil dust is
anthropogenic. They also suggest that studies of weekly cycles in
temperature, cloudiness, or precipitation should look for causes more in
light-absorbing particles and dust rather than sulfate or total aerosol.
There are also implications for personal exposure and epidemiological
studies of aerosol health effects.</abstract>
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</article>

