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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>9</volume_number>
		<issue_number>12</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acp-9-3911-2009</doi>
	<article_url>http://www.atmos-chem-phys.net/9/3911/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys.net/9/3911/2009/acp-9-3911-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys.net/9/3911/2009/acp-9-3911-2009.pdf</fulltext_pdf>
	<start_page>3911</start_page>
	<end_page>3934</end_page>
	<publication_date>2009-06-17</publication_date>
	<article_title content_type="html">Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>P. Martinerie</name>
			<email>patricia@lgge.obs.ujf-grenoble.fr</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>E. Nourtier-Mazauric</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>J.-M. Barnola</name>
		</author>
		<author numeration="4" affiliations="2">
			<name>W. T. Sturges</name>
		</author>
		<author numeration="5" affiliations="2,6">
			<name>D. R. Worton</name>
		</author>
		<author numeration="6" affiliations="3">
			<name>E. Atlas</name>
		</author>
		<author numeration="7" affiliations="4,7">
			<name>L. K. Gohar</name>
		</author>
		<author numeration="8" affiliations="4">
			<name>K. P. Shine</name>
		</author>
		<author numeration="9" affiliations="5">
			<name>G. P. Brasseur</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Laboratoire de Glaciologie et Géophysique de l&apos;Environnement (UMR CNRS/INSU 5183), CNRS, Université Joseph Fourier-Grenoble, BP 96, 38 402 Saint Martin d&apos;Hères, France</affiliation>
		<affiliation numeration="2" content_type="html">School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK</affiliation>
		<affiliation numeration="3" content_type="html">Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA</affiliation>
		<affiliation numeration="4" content_type="html">Department of Meteorology, University of Reading, Reading RG6 6BB, UK</affiliation>
		<affiliation numeration="5" content_type="html">National Center for Atmospheric Research, Boulder, CO 80307-3000, USA</affiliation>
		<affiliation numeration="6" content_type="html">now at: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3110, USA</affiliation>
		<affiliation numeration="7" content_type="html">now at: Met Office Hadley Centre, FitzRoy Road, Exeter. EX1 3PB, UK</affiliation>
	</affiliations>
	<abstract content_type="html">The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114,
CFC-115, CCl&lt;sub&gt;4&lt;/sub&gt; and SF&lt;sub&gt;6&lt;/sub&gt;) are studied by comparing measurements in polar
firn air from two Arctic and three Antarctic sites, and simulation results of
two numerical models: a 2-D atmospheric chemistry model and a 1-D firn
diffusion model. The first one is used to calculate atmospheric
concentrations from emission trends based on industrial inventories; the
calculated concentration trends are used by the second one to produce depth
concentration profiles in the firn. The 2-D atmospheric model is validated in
the boundary layer by comparison with atmospheric station measurements, and
vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn
air measurements provide constraints on historical atmospheric concentrations
over the last century. Age distributions in the firn are discussed using a
Green function approach. Finally, our results are used as input to a
radiative model in order to evaluate the radiative forcing of our target
gases. Multi-species and multi-site firn air studies allow to better
constrain atmospheric trends. The low concentrations of all studied gases at
the bottom of the firn, and their consistency with our model results confirm
that their natural sources are small. Our results indicate that the
emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF&lt;sub&gt;6&lt;/sub&gt;
are well constrained, whereas it is not the case for CFC-114 and CCl&lt;sub&gt;4&lt;/sub&gt;.
Significant emission-dependent changes in the lifetimes of halocarbons
destroyed in the stratosphere were obtained. Those result from the time
needed for their transport from the surface where they are emitted to the
stratosphere where they are destroyed. Efforts should be made to update and
reduce the large uncertainties on CFC lifetimes.</abstract>
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