In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences
Identifieur interne : 000050 ( Istex/Corpus ); précédent : 000049; suivant : 000051In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences
Auteurs : D. M. Cunnold ; L. P. Steele ; P. J. Fraser ; P. G. Simmonds ; R. G. Prinn ; R. F. Weiss ; L. W. Porter ; S. O'Doherty ; R. L. Langenfelds ; P. B. Krummel ; H. J. Wang ; L. Emmons ; X. X. Tie ; E. J. DlugokenckySource :
- Journal of Geophysical Research: Atmospheres [ 0148-0227 ] ; 2002-07-27.
Abstract
Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.
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DOI: 10.1029/2001JD001226
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Cunnold</name><affiliation><mods:affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</mods:affiliation></affiliation></author><author><name sortKey="Steele, L P" sort="Steele, L P" uniqKey="Steele L" first="L. P." last="Steele">L. P. Steele</name><affiliation><mods:affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</mods:affiliation></affiliation></author><author><name sortKey="Fraser, P J" sort="Fraser, P J" uniqKey="Fraser P" first="P. J." last="Fraser">P. J. Fraser</name><affiliation><mods:affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</mods:affiliation></affiliation></author><author><name sortKey="Simmonds, P G" sort="Simmonds, P G" uniqKey="Simmonds P" first="P. G." last="Simmonds">P. G. 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Krummel</name><affiliation><mods:affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</mods:affiliation></affiliation></author><author><name sortKey="Wang, H J" sort="Wang, H J" uniqKey="Wang H" first="H. J." last="Wang">H. J. Wang</name><affiliation><mods:affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</mods:affiliation></affiliation></author><author><name sortKey="Emmons, L" sort="Emmons, L" uniqKey="Emmons L" first="L." last="Emmons">L. Emmons</name><affiliation><mods:affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Tie, X X" sort="Tie, X X" uniqKey="Tie X" first="X. X." last="Tie">X. X. Tie</name><affiliation><mods:affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</mods:affiliation></affiliation></author><author><name sortKey="Dlugokencky, E J" sort="Dlugokencky, E J" uniqKey="Dlugokencky E" first="E. J." last="Dlugokencky">E. J. Dlugokencky</name><affiliation><mods:affiliation>Climate Monitoring and Diagnostics Laboratory, National Oceanic and Atmospheric Administration, Colorado, Boulder, USA</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Journal of Geophysical Research: Atmospheres</title><title level="j" type="abbrev">J.‐Geophys.‐Res.</title><idno type="ISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="2002-07-27">2002-07-27</date><biblScope unit="volume">107</biblScope><biblScope unit="issue">D14</biblScope><biblScope unit="page" from="ACH 20-1">ACH 20-1</biblScope><biblScope unit="page" to="ACH 20-18">ACH 20-18</biblScope></imprint><idno type="ISSN">0148-0227</idno></series><idno type="istex">2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4</idno><idno type="DOI">10.1029/2001JD001226</idno><idno type="ArticleID">2001JD001226</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0148-0227</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.</div></front></TEI><istex><corpusName>wiley</corpusName><author><json:item><name>D. M. Cunnold</name><affiliations><json:string>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</json:string></affiliations></json:item><json:item><name>L. P. Steele</name><affiliations><json:string>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</json:string></affiliations></json:item><json:item><name>P. J. Fraser</name><affiliations><json:string>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</json:string></affiliations></json:item><json:item><name>P. G. Simmonds</name><affiliations><json:string>School of Chemistry, University of Bristol, Bristol, UK</json:string></affiliations></json:item><json:item><name>R. G. Prinn</name><affiliations><json:string>Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Massachusetts, Cambridge, USA</json:string></affiliations></json:item><json:item><name>R. F. Weiss</name><affiliations><json:string>Scripps Institution of Oceanography, University of California at San Diego, California, La Jolla, USA</json:string></affiliations></json:item><json:item><name>L. W. Porter</name><affiliations><json:string>Cape Grim Baseline Air Pollution Station, Bureau of Meteorology, Smithton, Tasmania, Australia</json:string></affiliations></json:item><json:item><name>S. O'Doherty</name><affiliations><json:string>School of Chemistry, University of Bristol, Bristol, UK</json:string></affiliations></json:item><json:item><name>R. L. Langenfelds</name><affiliations><json:string>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</json:string></affiliations></json:item><json:item><name>P. B. Krummel</name><affiliations><json:string>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</json:string></affiliations></json:item><json:item><name>H. J. Wang</name><affiliations><json:string>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</json:string></affiliations></json:item><json:item><name>L. Emmons</name><affiliations><json:string>National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>X. X. Tie</name><affiliations><json:string>National Center for Atmospheric Research, Colorado, Boulder, USA</json:string></affiliations></json:item><json:item><name>E. J. Dlugokencky</name><affiliations><json:string>Climate Monitoring and Diagnostics Laboratory, National Oceanic and Atmospheric Administration, Colorado, Boulder, USA</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>methane measurements</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>methane modeling</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>tropospheric methane</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>methane trends</value></json:item></subject><language><json:string>eng</json:string></language><abstract>Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.</abstract><qualityIndicators><score>8.5</score><pdfVersion>1.4</pdfVersion><pdfPageSize>592 x 807 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>4</keywordCount><abstractCharCount>2275</abstractCharCount><pdfWordCount>13474</pdfWordCount><pdfCharCount>79048</pdfCharCount><pdfPageCount>20</pdfPageCount><abstractWordCount>366</abstractWordCount></qualityIndicators><title>In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title><genre><json:string>article</json:string></genre><host><volume>107</volume><pages><total>18</total><last>ACH 20-18</last><first>ACH 20-1</first></pages><issn><json:string>0148-0227</json:string></issn><issue>D14</issue><subject><json:item><value>Composition and Chemistry</value></json:item><json:item><value>ATMOSPHERIC COMPOSITION AND STRUCTURE</value></json:item><json:item><value>Constituent sources and sinks</value></json:item><json:item><value>Evolution of the atmosphere</value></json:item><json:item><value>Biosphere/atmosphere interactions</value></json:item><json:item><value>Biosphere/atmosphere interactions</value></json:item><json:item><value>Evolution of the atmosphere</value></json:item><json:item><value>GLOBAL CHANGE</value></json:item><json:item><value>Atmosphere</value></json:item><json:item><value>Atmosphere</value></json:item><json:item><value>TECTONOPHYSICS</value></json:item><json:item><value>Evolution of the Earth</value></json:item><json:item><value>Composition and Chemistry</value></json:item></subject><genre></genre><language><json:string>unknown</json:string></language><eissn><json:string>2156-2202</json:string></eissn><title>Journal of Geophysical Research: Atmospheres</title><doi><json:string>10.1002/(ISSN)2156-2202d</json:string></doi></host><publicationDate>2002</publicationDate><copyrightDate>2002</copyrightDate><doi><json:string>10.1029/2001JD001226</json:string></doi><id>2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4</id><fulltext><json:item><original>true</original><mimetype>application/pdf</mimetype><extension>pdf</extension><uri>https://api.istex.fr/document/2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4/fulltext/pdf</uri></json:item><json:item><original>false</original><mimetype>application/zip</mimetype><extension>zip</extension><uri>https://api.istex.fr/document/2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a" type="main" xml:lang="en">In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>Blackwell Publishing Ltd</publisher><availability><p>WILEY</p></availability><date>2002</date></publicationStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a" type="main" xml:lang="en">In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title><author><persName><forename type="first">D. M.</forename><surname>Cunnold</surname></persName><affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</affiliation></author><author><persName><forename type="first">L. P.</forename><surname>Steele</surname></persName><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation></author><author><persName><forename type="first">P. J.</forename><surname>Fraser</surname></persName><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation></author><author><persName><forename type="first">P. G.</forename><surname>Simmonds</surname></persName><affiliation>School of Chemistry, University of Bristol, Bristol, UK</affiliation></author><author><persName><forename type="first">R. G.</forename><surname>Prinn</surname></persName><affiliation>Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Massachusetts, Cambridge, USA</affiliation></author><author><persName><forename type="first">R. F.</forename><surname>Weiss</surname></persName><affiliation>Scripps Institution of Oceanography, University of California at San Diego, California, La Jolla, USA</affiliation></author><author><persName><forename type="first">L. W.</forename><surname>Porter</surname></persName><affiliation>Cape Grim Baseline Air Pollution Station, Bureau of Meteorology, Smithton, Tasmania, Australia</affiliation></author><author><persName><forename type="first">S.</forename><surname>O'Doherty</surname></persName><affiliation>School of Chemistry, University of Bristol, Bristol, UK</affiliation></author><author><persName><forename type="first">R. L.</forename><surname>Langenfelds</surname></persName><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation></author><author><persName><forename type="first">P. B.</forename><surname>Krummel</surname></persName><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation></author><author><persName><forename type="first">H. J.</forename><surname>Wang</surname></persName><affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</affiliation></author><author><persName><forename type="first">L.</forename><surname>Emmons</surname></persName><affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">X. X.</forename><surname>Tie</surname></persName><affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation></author><author><persName><forename type="first">E. J.</forename><surname>Dlugokencky</surname></persName><affiliation>Climate Monitoring and Diagnostics Laboratory, National Oceanic and Atmospheric Administration, Colorado, Boulder, USA</affiliation></author></analytic><monogr><title level="j">Journal of Geophysical Research: Atmospheres</title><title level="j" type="abbrev">J.‐Geophys.‐Res.</title><idno type="pISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><idno type="DOI">10.1002/(ISSN)2156-2202d</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="2002-07-27"></date><biblScope unit="volume">107</biblScope><biblScope unit="issue">D14</biblScope><biblScope unit="page" from="ACH 20-1">ACH 20-1</biblScope><biblScope unit="page" to="ACH 20-18">ACH 20-18</biblScope></imprint></monogr><idno type="istex">2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4</idno><idno type="DOI">10.1029/2001JD001226</idno><idno type="ArticleID">2001JD001226</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>2002</date></creation><langUsage><language ident="en">en</language></langUsage><abstract><p>Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.</p></abstract><textClass><keywords scheme="keyword"><list><head>Keywords</head><item><term>methane measurements</term></item><item><term>methane modeling</term></item><item><term>tropospheric methane</term></item><item><term>methane trends</term></item></list></keywords></textClass><textClass><keywords scheme="Journal Subject"><list><head>Index Terms</head><item><term>Composition and Chemistry</term></item><item><term>ATMOSPHERIC COMPOSITION AND STRUCTURE</term></item><item><term>Constituent sources and sinks</term></item><item><term>Evolution of the atmosphere</term></item><item><term>Biosphere/atmosphere interactions</term></item><item><term>Biosphere/atmosphere interactions</term></item><item><term>Evolution of the atmosphere</term></item><item><term>GLOBAL CHANGE</term></item><item><term>Atmosphere</term></item><item><term>Atmosphere</term></item><item><term>TECTONOPHYSICS</term></item><item><term>Evolution of the Earth</term></item></list></keywords></textClass><textClass><keywords scheme="Journal Subject"><list><head>article category</head><item><term>Composition and Chemistry</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="2001-08-16">Received</change><change when="2001-12-17">Registration</change><change when="2002-07-27">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><original>false</original><mimetype>text/plain</mimetype><extension>txt</extension><uri>https://api.istex.fr/document/2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Wiley, elements deleted: body"><istex:xmlDeclaration>version="1.0" encoding="UTF-8" standalone="yes"</istex:xmlDeclaration><istex:document><component type="serialArticle" version="2.0" xml:lang="en" xml:id="jgrd9311"><header><publicationMeta level="product"><doi>10.1002/(ISSN)2156-2202d</doi><issn type="print">0148-0227</issn><issn type="electronic">2156-2202</issn><idGroup><id type="product" value="JGRD"></id><id type="coden" value="JGREA2"></id></idGroup><titleGroup><title type="main" xml:lang="en" sort="JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES">Journal of Geophysical Research: Atmospheres</title><title type="short">J.‐Geophys.‐Res.</title></titleGroup></publicationMeta><publicationMeta level="part" position="140"><doi>10.1002/jgrd.v107.D14</doi><idGroup><id type="focusSection" value="4"></id></idGroup><titleGroup><title type="focusSection" xml:lang="en">Journal of Geophysical Research: Atmospheres</title></titleGroup><numberingGroup><numbering type="journalVolume" number="107">107</numbering><numbering type="journalIssue">D14</numbering></numberingGroup><coverDate startDate="2002-07-27">27 July 2002</coverDate></publicationMeta><publicationMeta level="unit" position="180" type="article" status="forIssue"><doi>10.1029/2001JD001226</doi><idGroup><id type="editorialOffice" value="2001JD001226"></id><id type="unit" value="JGRD9311"></id></idGroup><countGroup><count type="pageTotal" number="18"></count></countGroup><titleGroup><title type="articleCategory">Composition and Chemistry</title><title type="tocHeading1">Composition and Chemistry</title></titleGroup><copyright ownership="thirdParty">Copyright 2002 by the American Geophysical Union.</copyright><eventGroup><event type="manuscriptReceived" date="2001-08-16"></event><event type="manuscriptRevised" date="2001-11-21"></event><event type="manuscriptAccepted" date="2001-12-17"></event><event type="firstOnline" date="2002-07-31"></event><event type="publishedOnlineFinalForm" date="2002-07-31"></event><event type="xmlConverted" agent="SPi Global Converter:AGUv3.2_TO_WileyML3Gv1.0.3 version:1.1; 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M.</givenNames></author>, et al., <articleTitle>In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</articleTitle>, <journalTitle>J. Geophys. Res.</journalTitle>, <vol>107</vol>(<issue>D14</issue>), doi:<accessionId ref="info:doi/10.1029/2001JD001226">10.1029/2001JD001226</accessionId>, <pubYear year="2002">2002</pubYear>.</citation></selfCitationGroup><linkGroup><link type="toTypesetVersion" href="file:JGRD.JGRD9311.pdf"></link></linkGroup></publicationMeta><contentMeta><countGroup><count type="figureTotal" number="8"></count><count type="tableTotal" number="5"></count></countGroup><titleGroup><title type="main">In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title><title type="short">GAGE/AGAGE METHANE FROM 1985–2000</title><title type="shortAuthors">Cunnold <i>et al</i>.</title></titleGroup><creators><creator creatorRole="author" xml:id="jgrd9311-cr-0001" affiliationRef="#jgrd9311-aff-0001"><personName><givenNames>D. M.</givenNames> <familyName>Cunnold</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0002" affiliationRef="#jgrd9311-aff-0002"><personName><givenNames>L. P.</givenNames> <familyName>Steele</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0003" affiliationRef="#jgrd9311-aff-0002"><personName><givenNames>P. J.</givenNames> <familyName>Fraser</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0004" affiliationRef="#jgrd9311-aff-0003"><personName><givenNames>P. G.</givenNames> <familyName>Simmonds</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0005" affiliationRef="#jgrd9311-aff-0004"><personName><givenNames>R. G.</givenNames> <familyName>Prinn</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0006" affiliationRef="#jgrd9311-aff-0005"><personName><givenNames>R. F.</givenNames> <familyName>Weiss</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0007" affiliationRef="#jgrd9311-aff-0006"><personName><givenNames>L. W.</givenNames> <familyName>Porter</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0008" affiliationRef="#jgrd9311-aff-0003"><personName><givenNames>S.</givenNames> <familyName>O'Doherty</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0009" affiliationRef="#jgrd9311-aff-0002"><personName><givenNames>R. L.</givenNames> <familyName>Langenfelds</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0010" affiliationRef="#jgrd9311-aff-0002"><personName><givenNames>P. B.</givenNames> <familyName>Krummel</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0011" affiliationRef="#jgrd9311-aff-0001"><personName><givenNames>H. J.</givenNames> <familyName>Wang</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0012" affiliationRef="#jgrd9311-aff-0007"><personName><givenNames>L.</givenNames> <familyName>Emmons</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0013" affiliationRef="#jgrd9311-aff-0007"><personName><givenNames>X. X.</givenNames> <familyName>Tie</familyName></personName></creator><creator creatorRole="author" xml:id="jgrd9311-cr-0014" affiliationRef="#jgrd9311-aff-0008"><personName><givenNames>E. J.</givenNames> <familyName>Dlugokencky</familyName></personName></creator></creators><affiliationGroup><affiliation countryCode="US" type="organization" xml:id="jgrd9311-aff-0001"><orgDiv>School of Earth and Atmospheric Sciences</orgDiv><orgName>Georgia Institute of Technology</orgName><address><city>Atlanta</city><countryPart>Georgia</countryPart><country>USA</country></address></affiliation><affiliation countryCode="AU" type="organization" xml:id="jgrd9311-aff-0002"><orgDiv>Atmospheric Research</orgDiv><orgName>Commonwealth Scientific and Industrial Research Organization</orgName><address><city>Aspendale</city><countryPart>Victoria</countryPart><country>Australia</country></address></affiliation><affiliation countryCode="GB" type="organization" xml:id="jgrd9311-aff-0003"><orgDiv>School of Chemistry</orgDiv><orgName>University of Bristol</orgName><address><city>Bristol</city><country>UK</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd9311-aff-0004"><orgDiv>Department of Earth, Atmospheric and Planetary Sciences</orgDiv><orgName>Massachusetts Institute of Technology</orgName><address><city>Cambridge</city><countryPart>Massachusetts</countryPart><country>USA</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd9311-aff-0005"><orgDiv>Scripps Institution of Oceanography</orgDiv><orgName>University of California at San Diego</orgName><address><city>La Jolla</city><countryPart>California</countryPart><country>USA</country></address></affiliation><affiliation countryCode="AU" type="organization" xml:id="jgrd9311-aff-0006"><orgDiv>Cape Grim Baseline Air Pollution Station</orgDiv><orgName>Bureau of Meteorology, Smithton</orgName><address><city>Tasmania</city><country>Australia</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd9311-aff-0007"><orgName>National Center for Atmospheric Research</orgName><address><city>Boulder</city><countryPart>Colorado</countryPart><country>USA</country></address></affiliation><affiliation countryCode="US" type="organization" xml:id="jgrd9311-aff-0008"><orgDiv>Climate Monitoring and Diagnostics Laboratory</orgDiv><orgName>National Oceanic and Atmospheric Administration</orgName><address><city>Boulder</city><countryPart>Colorado</countryPart><country>USA</country></address></affiliation></affiliationGroup><keywordGroup type="author"><keyword xml:id="jgrd9311-kwd-0001">methane measurements</keyword><keyword xml:id="jgrd9311-kwd-0002">methane modeling</keyword><keyword xml:id="jgrd9311-kwd-0003">tropospheric methane</keyword><keyword xml:id="jgrd9311-kwd-0004">methane trends</keyword></keywordGroup><abstractGroup><abstract type="main"><p xml:id="jgrd9311-para-0001" label="1">Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH<sub>4</sub> with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by <link href="#jgrd9311-bib-0050"><i>Prinn et al.</i> [2001]</link> is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from <link href="#jgrd9311-bib-0054"><i>Spivakovsky et al.</i> [2000]</link> provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with <link href="#jgrd9311-bib-0050"><i>Prinn et al.</i> [2001]</link> for the Southern Hemisphere.</p></abstract></abstractGroup></contentMeta></header></component></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title></titleInfo><titleInfo type="abbreviated"><title>GAGE/AGAGE METHANE FROM 1985–2000</title></titleInfo><titleInfo type="alternative" contentType="CDATA" lang="en"><title>In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences</title></titleInfo><name type="personal"><namePart type="given">D. M.</namePart><namePart type="family">Cunnold</namePart><affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">L. P.</namePart><namePart type="family">Steele</namePart><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">P. J.</namePart><namePart type="family">Fraser</namePart><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">P. G.</namePart><namePart type="family">Simmonds</namePart><affiliation>School of Chemistry, University of Bristol, Bristol, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">R. G.</namePart><namePart type="family">Prinn</namePart><affiliation>Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Massachusetts, Cambridge, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">R. F.</namePart><namePart type="family">Weiss</namePart><affiliation>Scripps Institution of Oceanography, University of California at San Diego, California, La Jolla, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">L. W.</namePart><namePart type="family">Porter</namePart><affiliation>Cape Grim Baseline Air Pollution Station, Bureau of Meteorology, Smithton, Tasmania, Australia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">S.</namePart><namePart type="family">O'Doherty</namePart><affiliation>School of Chemistry, University of Bristol, Bristol, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">R. L.</namePart><namePart type="family">Langenfelds</namePart><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">P. B.</namePart><namePart type="family">Krummel</namePart><affiliation>Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, Victoria, Aspendale, Australia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">H. J.</namePart><namePart type="family">Wang</namePart><affiliation>School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Georgia, Atlanta, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">L.</namePart><namePart type="family">Emmons</namePart><affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">X. X.</namePart><namePart type="family">Tie</namePart><affiliation>National Center for Atmospheric Research, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">E. J.</namePart><namePart type="family">Dlugokencky</namePart><affiliation>Climate Monitoring and Diagnostics Laboratory, National Oceanic and Atmospheric Administration, Colorado, Boulder, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="article">article</genre><originInfo><publisher>Blackwell Publishing Ltd</publisher><dateIssued encoding="w3cdtf">2002-07-27</dateIssued><dateCaptured encoding="w3cdtf">2001-08-16</dateCaptured><dateValid encoding="w3cdtf">2001-12-17</dateValid><edition>Cunnold, D. M., et al., In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences, J. Geophys. Res., 107(D14), doi:10.1029/2001JD001226, 2002.</edition><copyrightDate encoding="w3cdtf">2002</copyrightDate></originInfo><language><languageTerm type="code" authority="rfc3066">en</languageTerm><languageTerm type="code" authority="iso639-2b">eng</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType><extent unit="figures">8</extent><extent unit="tables">5</extent></physicalDescription><abstract>Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12‐box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid‐1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two‐dimensional (2‐D), 12‐box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2‐D estimation procedure using the 3‐D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2‐D simulation of methane. The 2‐D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12‐month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.</abstract><subject><genre>Keywords</genre><topic>methane measurements</topic><topic>methane modeling</topic><topic>tropospheric methane</topic><topic>methane trends</topic></subject><relatedItem type="host"><titleInfo><title>Journal of Geophysical Research: Atmospheres</title></titleInfo><titleInfo type="abbreviated"><title>J.‐Geophys.‐Res.</title></titleInfo><subject><genre>Index Terms</genre><topic authorityURI="http://psi.agu.org/subset/ACH">Composition and Chemistry</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0300">ATMOSPHERIC COMPOSITION AND STRUCTURE</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0322">Constituent sources and sinks</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0325">Evolution of the atmosphere</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0315">Biosphere/atmosphere interactions</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0315">Biosphere/atmosphere interactions</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0325">Evolution of the atmosphere</topic><topic authorityURI="http://psi.agu.org/taxonomy5/1600">GLOBAL CHANGE</topic><topic authorityURI="http://psi.agu.org/taxonomy5/1610">Atmosphere</topic><topic authorityURI="http://psi.agu.org/taxonomy5/1610">Atmosphere</topic><topic authorityURI="http://psi.agu.org/taxonomy5/8100">TECTONOPHYSICS</topic><topic authorityURI="http://psi.agu.org/taxonomy5/8125">Evolution of the Earth</topic></subject><subject><genre>article category</genre><topic>Composition and Chemistry</topic></subject><identifier type="ISSN">0148-0227</identifier><identifier type="eISSN">2156-2202</identifier><identifier type="DOI">10.1002/(ISSN)2156-2202d</identifier><identifier type="CODEN">JGREA2</identifier><identifier type="PublisherID">JGRD</identifier><part><date>2002</date><detail type="volume"><caption>vol.</caption><number>107</number></detail><detail type="issue"><caption>no.</caption><number>D14</number></detail><extent unit="pages"><start>ACH 20-1</start><end>ACH 20-18</end><total>18</total></extent></part></relatedItem><identifier type="istex">2C5C3C36C6626A8E073806A6BEDA60F2574DB1D4</identifier><identifier type="DOI">10.1029/2001JD001226</identifier><identifier type="ArticleID">2001JD001226</identifier><accessCondition type="use and reproduction" contentType="copyright">Copyright 2002 by the American Geophysical Union.</accessCondition><recordInfo><recordContentSource>WILEY</recordContentSource></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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