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<front>
<journal-meta>
<journal-id journal-id-type="publisher">AMT</journal-id>
<journal-title-group>
<journal-title>Atmospheric Measurement Techniques</journal-title>
<abbrev-journal-title abbrev-type="publisher">AMT</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Atmos. Meas. Tech.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1867-8548</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/amt-5-2689-2012</article-id>
<title-group>
<article-title>Effect of air composition (N&lt;sub&gt;2&lt;/sub&gt;, O&lt;sub&gt;2&lt;/sub&gt;, Ar, and H&lt;sub&gt;2&lt;/sub&gt;O) on CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; measurement by wavelength-scanned cavity ring-down spectroscopy: calibration and measurement strategy</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nara</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tanimoto</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tohjima</surname>
<given-names>Y.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Mukai</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nojiri</surname>
<given-names>Y.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Katsumata</surname>
<given-names>K.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Rella</surname>
<given-names>C. W.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Picarro Inc., 3105 Patrick Henry Drive, California, Santa Clara, 94054, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>12</day>
<month>11</month>
<year>2012</year>
</pub-date>
<volume>5</volume>
<issue>11</issue>
<fpage>2689</fpage>
<lpage>2701</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2012 H. Nara et al.</copyright-statement>
<copyright-year>2012</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://amt.copernicus.org/articles/5/2689/2012/amt-5-2689-2012.html">This article is available from https://amt.copernicus.org/articles/5/2689/2012/amt-5-2689-2012.html</self-uri>
<self-uri xlink:href="https://amt.copernicus.org/articles/5/2689/2012/amt-5-2689-2012.pdf">The full text article is available as a PDF file from https://amt.copernicus.org/articles/5/2689/2012/amt-5-2689-2012.pdf</self-uri>
<abstract>
<p>We examined potential interferences from water vapor and atmospheric
background gases (N&lt;sub&gt;2&lt;/sub&gt;, O&lt;sub&gt;2&lt;/sub&gt;, and Ar), and biases by isotopologues of
target species, on accurate measurement of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt;
by means of wavelength-scanned cavity ring-down spectroscopy (WS-CRDS).
Changes of the background gas mole fractions in the sample air substantially
impacted the CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; measurements: variation of CO&lt;sub&gt;2&lt;/sub&gt; and
CH&lt;sub&gt;4&lt;/sub&gt; due to relative increase of each background gas increased as Ar
&lt; O&lt;sub&gt;2&lt;/sub&gt; &lt; N&lt;sub&gt;2&lt;/sub&gt;, suggesting similar relation for the
pressure-broadening effects (PBEs) among the background gas. The
pressure-broadening coefficients due to variations in O&lt;sub&gt;2&lt;/sub&gt; and Ar for
CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; are empirically determined from these experimental
results. Calculated PBEs using the pressure-broadening coefficients are
linearly correlated with the differences between the mole fractions of
O&lt;sub&gt;2&lt;/sub&gt; and Ar and their ambient abundances. Although the PBEs calculation
showed that impact of natural variation of O&lt;sub&gt;2&lt;/sub&gt; is negligible on the
CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; measurements, significant bias was inferred for the
measurement of synthetic standard gases. For gas standards balanced with
purified air, the PBEs were estimated to be marginal (up to 0.05 ppm for
CO&lt;sub&gt;2&lt;/sub&gt; and 0.01 ppb for CH&lt;sub&gt;4&lt;/sub&gt;) although the PBEs were substantial (up
to 0.87 ppm for CO&lt;sub&gt;2&lt;/sub&gt; and 1.4 ppb for CH&lt;sub&gt;4&lt;/sub&gt;) for standards balanced
with synthetic air. For isotopic biases on CO&lt;sub&gt;2&lt;/sub&gt; measurements, we
compared experimental results and theoretical calculations, which showed
excellent agreement within their uncertainty. We derived instrument-specific
water correction functions empirically for three WS-CRDS instruments
(Picarro EnviroSense 3000i, G-1301, and G-2301), and evaluated the
transferability of the water correction function from G-1301 among these
instruments. Although the transferability was not proven, no significant
difference was found in the water vapor correction function for the
investigated WS-CRDS instruments as well as the instruments reported in the
past studies within the typical analytical precision at sufficiently low
water concentrations (&lt;0.7% for CO&lt;sub&gt;2&lt;/sub&gt; and &lt;0.6% for CH&lt;sub&gt;4&lt;/sub&gt;).
For accurate measurements of CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in ambient
air, we concluded that WS-CRDS measurements should be performed under
complete dehumidification of air samples, or moderate dehumidification
followed by application of a water vapor correction function, along with
calibration by natural air-based standard gases or purified air-balanced
synthetic standard gases with the isotopic correction.</p>
</abstract>
<counts><page-count count="13"/></counts>
</article-meta>
</front>
<body/>
<back>
<ref-list>
<title>References</title>
<ref id="ref1">
<label>1</label><mixed-citation publication-type="other" xlink:type="simple">Allison, C. E. and Francey, R. J.: Verifying Southern Hemisphere trends in atmospheric carbon dioxide stable isotopes, J. Geophys. Res., 112, D21304, &lt;a href=&quot;http://dx.doi.org/10.1029/2006JD007345&quot;&gt;https://doi.org/10.1029/2006JD007345&lt;/a&gt;, 2007.</mixed-citation>
</ref>
<ref id="ref2">
<label>2</label><mixed-citation publication-type="other" xlink:type="simple">Aydin, M., Verhulst, K. R., Saltzman, E. S., Battle, M. O., Monzka, S. A., Blake, D. R., Tang, Q., and Prather, M. J.: Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air, Nature, 476, 198–202, &lt;a href=&quot;http://dx.doi.org/10.1038/nature10352&quot;&gt;https://doi.org/10.1038/nature10352&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref3">
<label>3</label><mixed-citation publication-type="other" xlink:type="simple">Baer, D. S., Paul, J. B., Gupta, M., and O&apos;Keefe, A.: Sensitive absorption measurements in the near-infrared region using off-axis integrated-cavity-output spectroscopy, Appl. Phys. B, 75, 261–265, &lt;a href=&quot;http://dx.doi.org/10.1007/s00340-002-0971-z&quot;&gt;https://doi.org/10.1007/s00340-002-0971-z&lt;/a&gt;, 2002.</mixed-citation>
</ref>
<ref id="ref4">
<label>4</label><mixed-citation publication-type="other" xlink:type="simple">Berden, G., Petters, R., and Meijer, G.: Cavity-enhanced absorption spectroscopy of the 1.5 μm band system of jet-cooled ammnonia, Chem. Phys. Lett., 307, 131–138, 1999.</mixed-citation>
</ref>
<ref id="ref5">
<label>5</label><mixed-citation publication-type="other" xlink:type="simple">Bischof, W.: The influence of the carrier gas on the infrared gas analysis of atmospheric CO&lt;sub&gt;2&lt;/sub&gt;, Tellus, 27, 59–61, 1975.</mixed-citation>
</ref>
<ref id="ref6">
<label>6</label><mixed-citation publication-type="other" xlink:type="simple">Brenninkmeijer, C. A. M., Crutzen, P., Boumard, F., Dauer, T., Dix, B., Ebinghaus, R., Filippi, D., Fischer, H., Franke, H., Frie{ß}, U., Heintzenberg, J., Helleis, F., Hermann, M., Kock, H. H., Koeppel, C., Lelieveld, J., Leuenberger, M., Martinsson, B. G., Miemczyk, S., Moret, H. P., Nguyen, H. N., Nyfeler, P., Oram, D., O&apos;Sullivan, D., Penkett, S., Platt, U., Pupek, M., Ramonet, M., Randa, B., Reichelt, M., Rhee, T. S., Rohwer, J., Rosenfeld, K., Scharffe, D., Schlager, H., Schumann, U., Slemr, F., Sprung, D., Stock, P., Thaler, R., Valentino, F., van Velthoven, P., Waibel, A., Wandel, A., Waschitschek, K., Wiedensohler, A., Xueref-Remy, I., Zahn, A., Zech, U., and Ziereis, H.: Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system, Atmos. Chem. Phys., 7, 4953–4976, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-7-4953-2007&quot;&gt;https://doi.org/10.5194/acp-7-4953-2007&lt;/a&gt;, 2007.</mixed-citation>
</ref>
<ref id="ref7">
<label>7</label><mixed-citation publication-type="other" xlink:type="simple">Buchwitz, M., de Beek, R., Burrows, J. P., Bovensmann, H., Warneke, T., Notholt, J., Meirink, J. F., Goede, A. P. H., Bergamaschi, P., Körner, S., Heimann, M., and Schulz, A.: Atmospheric methane and carbon dioxide from SCIAMACHY satellite data: initial comparison with chemistry and transport models, Atmos. Chem. Phys., 5, 941–962, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-5-941-2005&quot;&gt;https://doi.org/10.5194/acp-5-941-2005&lt;/a&gt;, 2005.</mixed-citation>
</ref>
<ref id="ref8">
<label>8</label><mixed-citation publication-type="other" xlink:type="simple">Chen, H., Winderlich, J., Gerbig, C., Hoefer, A., Rella, C. W., Crosson, E. R., Van Pelt, A. D., Steinbach, J., Kolle, O., Beck, V., Daube, B. C., Gottlieb, E. W., Chow, V. Y., Santoni, G. W., and Wofsy, S. C.: High-accuracy continuous airborne measurements of greenhouse gases (CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt;) using the cavity ring-down spectroscopy (CRDS) technique, Atmos. Meas. Tech., 3, 375–386, &lt;a href=&quot;http://dx.doi.org/10.5194/amt-3-375-2010&quot;&gt;https://doi.org/10.5194/amt-3-375-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref9">
<label>9</label><mixed-citation publication-type="other" xlink:type="simple">Cunnold, D. M., Steele, L. P., Fraser, P. J., Simmonds, P. G., Prinn, R. G., Weiss, R. F., Porter, L. W., O&apos;Doherty, S., Langenfelds, R. L., Krummel, P. B., Wang, H. J., Emmons, L., Tie, X. X., and Dlugokencky, E. J.: In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences, J. Geophys. Res., 107,  4225, &lt;a href=&quot;http://dx.doi.org/10.1029/2001JD001226&quot;&gt;https://doi.org/10.1029/2001JD001226&lt;/a&gt;, 2002.</mixed-citation>
</ref>
<ref id="ref10">
<label>10</label><mixed-citation publication-type="other" xlink:type="simple">Conway, T., Tans, P. P., Waterman, L. S., Thoning, K. W., Kitzis, D. R., Masarie, K. A., and Zhang, N.: Evidence for interannual variability of the carbon cycle from the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network, J. Geophys. Res., 99, 22831–22855, 1994.</mixed-citation>
</ref>
<ref id="ref11">
<label>11</label><mixed-citation publication-type="other" xlink:type="simple">Coplen, T. B., Bohlke, J. K., De Bievre, P., Ding, T., Holden, N. E., Hopple, J. A., Krouse, H. R., Lamberty, A., Peiser, H. S., Revesz, K., Rieder, S. E., Rosman, K. J. R., Roth, E., Taylor, P. D. P., Vocke, R. D., and Xiao, Y. K.: Isotope-abundance variations of selected elements – (IUPAC Technical Report), Pure Appl. Chem., 74, 1987–2017, 2002.</mixed-citation>
</ref>
<ref id="ref12">
<label>12</label><mixed-citation publication-type="other" xlink:type="simple">Crosson, E. R.: A cavity ring-down analyzer for measuring atmospheric levels of methane, carbon dioxide, and water vapor, Appl. Phys. B-Lasers O., 92, 403–408, 2008.</mixed-citation>
</ref>
<ref id="ref13">
<label>13</label><mixed-citation publication-type="other" xlink:type="simple">Dlugokencky, E. J., Steele, L. P., Lang, P. M., and Masarie, K. A.: Atmospheric methane at Mauna Loa and Barrow observaties: Presentation and analysis of in situ measurements, J. Geophys. Res., 100,  23103–23113, 1995.</mixed-citation>
</ref>
<ref id="ref14">
<label>14</label><mixed-citation publication-type="other" xlink:type="simple">Dicke, R.: The effect of collisions upon the Doppler width of spectral lines, Phys. Rev., 89, 472–473, 1953.</mixed-citation>
</ref>
<ref id="ref15">
<label>15</label><mixed-citation publication-type="other" xlink:type="simple">Esler, M. B., Griffith, D. W. T., Wilson, S. R., and Steele, L. P.: Precision trace gas analysis by FT-IR spectroscopy. 1. Simultaneous analysis of CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, and CO in Air, Anal. Chem., 72, 206–215, 2000.</mixed-citation>
</ref>
<ref id="ref16">
<label>16</label><mixed-citation publication-type="other" xlink:type="simple">Galatry, L.: Simultaneous effect of Doppler and foreign gas broadening on spectral lines, Phy. Rev. 122, 1218–1223, 1961.</mixed-citation>
</ref>
<ref id="ref17">
<label>17</label><mixed-citation publication-type="other" xlink:type="simple">GLOBALVIEW-CO2C13: Cooperative Atmospheric Data Integration Project – δ&lt;sup&gt;13&lt;/sup&gt;C of Carbon Dioxide, CD-ROM, NOAA ESRL, Boulder, Colorado, also available via anonymous FTP to &lt;a href=&quot;ftp.cmdl.noaa.gov&quot;&gt;ftp.cmdl.noaa.gov&lt;/a&gt;, Path: &lt;a href=&quot;ccg/co2c13/GLOBALVIEW&quot;&gt;ccg/co2c13/GLOBALVIEW&lt;/a&gt; (last access: 12&amp;nbsp;November&amp;nbsp;2012), 2009.</mixed-citation>
</ref>
<ref id="ref18">
<label>18</label><mixed-citation publication-type="other" xlink:type="simple">Griffith, D. W. T.: Calculations of carrier gas effects in non-dispersive infrared analyzers I. Theory, Tellus, 34, 376–384, 1982.</mixed-citation>
</ref>
<ref id="ref19">
<label>19</label><mixed-citation publication-type="other" xlink:type="simple">Griffith, D. W. T., Deutscher, N. M., Caldow, C. G. R., Kettlewell, G., Riggenbach, M., and Hammer, S.: A Fourier transform infrared trace gas analyser for atmospheric applications, Atmos. Meas. Tech. Discuss., 5, 3717–3769, &lt;a href=&quot;http://dx.doi.org/10.5194/amtd-5-3717-2012&quot;&gt;https://doi.org/10.5194/amtd-5-3717-2012&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref20">
<label>20</label><mixed-citation publication-type="other" xlink:type="simple">Griffith, D. W. T., Keeling, C. D., Adams, J. A., Guenther, P. R., and Bacastow, R. B.: Calculations of carrier gas effects in non-dispersive infrared analyzers. II. Comparisons with experiment, Tellus, 34, 385–397, 1982.</mixed-citation>
</ref>
<ref id="ref21">
<label>21</label><mixed-citation publication-type="other" xlink:type="simple">Grutter, M.: Multi-gas analysis of ambient air using FTIR spectroscopy over Mexico city, Atmósfera, 16, 1–13, 2003.</mixed-citation>
</ref>
<ref id="ref22">
<label>22</label><mixed-citation publication-type="other" xlink:type="simple">Hammer, S., Griffith, D. W. T., Konrad, G., Vardag, S., Caldow, C., and Levin, I.: Assessment of a multi-species in-situ FTIR for precise atmospheric greenhouse gas observations, Atmos. Meas. Tech. Discuss., 5, 3645–3692, &lt;a href=&quot;http://dx.doi.org/10.5194/amtd-5-3645-2012&quot;&gt;https://doi.org/10.5194/amtd-5-3645-2012&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref23">
<label>23</label><mixed-citation publication-type="other" xlink:type="simple">Kai, F. M., Tyler, S. C., Randerson, J. T., and Blake, D. R.: Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources, Nature, 476, 194–197, &lt;a href=&quot;http://dx.doi.org/10.1038/nature10259&quot;&gt;https://doi.org/10.1038/nature10259&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref24">
<label>24</label><mixed-citation publication-type="other" xlink:type="simple">Keeling, C. D.: The concentration and isotopic abundances of carbon dioxide in the atmosphere, Tellus, 12, 200–203, 1960.</mixed-citation>
</ref>
<ref id="ref25">
<label>25</label><mixed-citation publication-type="other" xlink:type="simple">Keeling, C. D., Whorf, T. P., Wahlen, M., and van der Plicht, J.: Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980, Nature, 375, 666–670, 1995.</mixed-citation>
</ref>
<ref id="ref26">
<label>26</label><mixed-citation publication-type="other" xlink:type="simple">Keeling, R. F. and Shertz, S. R.: Seasonal and interannual variations in atmospheric oxygen and implications for the global carbon cycle, Nature, 358, 723–727, 1992.</mixed-citation>
</ref>
<ref id="ref27">
<label>27</label><mixed-citation publication-type="other" xlink:type="simple">Keeling, R. F., Blaine, T., Paplawsky, B., Katz, L., Atwood, C., and Brockwell, T.: Measurement of changes in atmospheric Ar/N&lt;sub&gt;2&lt;/sub&gt; ratio using a rapid-switching, single-capillary mass spectrometer system, Tellus, 56B, 322–338, 2004.</mixed-citation>
</ref>
<ref id="ref28">
<label>28</label><mixed-citation publication-type="other" xlink:type="simple">Kozlova, E. A. and Manning, A. C.: Methodology and calibration for continuous measurements of biogeochemical trace gas and O&lt;sub&gt;2&lt;/sub&gt; concentrations from a 300-m tall tower in central Siberia, Atmos. Meas. Tech., 2, 205–220, &lt;a href=&quot;http://dx.doi.org/10.5194/amt-2-205-2009&quot;&gt;https://doi.org/10.5194/amt-2-205-2009&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref29">
<label>29</label><mixed-citation publication-type="other" xlink:type="simple">Lowe, D. C., Guenther, P. R., and Keeling, C. D.: The concentration of atmospheric carbon dioxide at Baring Head, New Zealand, Tellus, 31, 58–67, 1979.</mixed-citation>
</ref>
<ref id="ref30">
<label>30</label><mixed-citation publication-type="other" xlink:type="simple">Machida, T., Matsueda, H., Sawa, Y., Nakagawa, Y., Hirotani, K., Kondo, N., Goto, K., Nakazawa, T., Ishikawa, K., and Ogawa, T.: Worldwide measurements of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; and other trace gas species using commercial airlines, J. Atmos. Oceanic Technol., 25, 1744–1754, 2008.</mixed-citation>
</ref>
<ref id="ref31">
<label>31</label><mixed-citation publication-type="other" xlink:type="simple">Marquis, M. and Tans, P.: Carbon Crucible, Science, 320, 460–461, 2008.</mixed-citation>
</ref>
<ref id="ref32">
<label>32</label><mixed-citation publication-type="other" xlink:type="simple">Matsueda, H. and Inoue, H. Y.: Measurements of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; using a commercial airliner from 1993 to 1994, Atmos. Environ., 30, 1647–1655, 1996.</mixed-citation>
</ref>
<ref id="ref33">
<label>33</label><mixed-citation publication-type="other" xlink:type="simple">Messerschmidt, J., Geibel, M. C., Blumenstock, T., Chen, H., Deutscher, N. M., Engel, A., Feist, D. G., Gerbig, C., Gisi, M., Hase, F., Katrynski, K., Kolle, O., Lavricč, J. V., Notholt, J., Palm, M., Ramonet, M., Rettinger, M., Schmidt, M., Sussmann, R., Toon, G. C., Truong, F., Warneke, T., Wennberg, P. O., Wunch, D., and Xueref-Remy, I.: Calibration of TCCON column-averaged CO&lt;sub&gt;2&lt;/sub&gt;: the first aircraft campaign over European TCCON sites, Atmos. Chem. Phys., 11, 10765–10777, &lt;a href=&quot;http://dx.doi.org/10.5194/acp-11-10765-2011&quot;&gt;https://doi.org/10.5194/acp-11-10765-2011&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref34">
<label>34</label><mixed-citation publication-type="other" xlink:type="simple">Montzka, S. A., Dolugokencky, E. J., and Butler, J. H.: Non-CO&lt;sub&gt;2&lt;/sub&gt; greenhouse gases and climate change, Nature, 476, 43–50, &lt;a href=&quot;http://dx.doi.org/10.1038/nature10322&quot;&gt;https://doi.org/10.1038/nature10322&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref35">
<label>35</label><mixed-citation publication-type="other" xlink:type="simple">Nakamichi, S., Kawaguchi, Y., Fukuda, H., Enami, S., Hashimoto, Satoshi, Kawasaki, M., Umekawa, T., Morino, I., Suto, H., and Inoue, G.: Buffer-gas pressure broadening for the (3 0&lt;sup&gt;0&lt;/sup&gt; 1)$_III  \leftarrow $ (0 0 0) band of CO&lt;sub&gt;2&lt;/sub&gt; measured with continuous-wave cavity ring-down spectroscopy, Phys. Chem. Chem. Phys., 8, 364–368, 2006.</mixed-citation>
</ref>
<ref id="ref36">
<label>36</label><mixed-citation publication-type="other" xlink:type="simple">O&apos;Keefe, A.: Integrated cavity output analysis of ultra-weak absorption, Chem. Phys. Lett., 293, 331–336, 1998.</mixed-citation>
</ref>
<ref id="ref37">
<label>37</label><mixed-citation publication-type="other" xlink:type="simple">O&apos;Keefe, A. and Deacon, A., G.: Cavity ring-down optical sectrometer for absorption measurements using pulsed laser sources, Rev. Sci. Instrum., 59, 2544–2554, 1988.</mixed-citation>
</ref>
<ref id="ref38">
<label>38</label><mixed-citation publication-type="other" xlink:type="simple">O&apos;Keefe, A., Scherer, J. J., and Paul, J. B.: Integrated cavity output spectroscopy, Chem. Phys. Lett., 307, 343–349, 1999.</mixed-citation>
</ref>
<ref id="ref39">
<label>39</label><mixed-citation publication-type="other" xlink:type="simple">Paul, J. B., Lapson, L., and Anderson, J. G.: Ultrasensitive absorption spectroscopy with a high-finesse optical cavity and off-axis alignment, Appl. Opt., 40, 4901–4910, 2001.</mixed-citation>
</ref>
<ref id="ref40">
<label>40</label><mixed-citation publication-type="other" xlink:type="simple">Pearman, G. I. and Garratt, J. R.: Errors in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentration measurements arising from the use of reference gas mixtgures different in composition to the sample air, Tellus, 27, 62–66, 1975.</mixed-citation>
</ref>
<ref id="ref41">
<label>41</label><mixed-citation publication-type="other" xlink:type="simple">Prinn, R. G., Weiss, R. F., Fraser, P. J., Simmonds, P. G., Cunnold, D. M., Alyea, F. N., O&apos;Doherty, S., Salameh, P., Miller, B. R., Huang, J., Wang, R. H. J., Hartley, D. E., Harth, C., Steele, L. P., Sturrock, G., Midgley, P. M., and McCulloch, A.: A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE, J. Geophys. Res., 105, 17751–17792, 2000.</mixed-citation>
</ref>
<ref id="ref42">
<label>42</label><mixed-citation publication-type="other" xlink:type="simple">Quay, P. D., Stutsman, J., Wilbur, D., Snover, A., Dlugokencky, E., and Brown, T.: The isotopic composition of atmospheric methane, Global Biogeochem. Cy., 13, 445–461, 1999.</mixed-citation>
</ref>
<ref id="ref43">
<label>43</label><mixed-citation publication-type="other" xlink:type="simple">Richard, E. C., Kelly, K. K., Winkler, R. H., Wilson, R., Thompson, T. L., Mclaughlin, R. J., Schmeltekopf, A. L., and Tuck, A. F.: A fast-response near-infrared tunable diode laser absorption spectrometer for in situ measurements of CH&lt;sub&gt;4&lt;/sub&gt; in the upper troposphere and lower stratosphere, Appl. Phys. B75, 183–194, &lt;a href=&quot;http://dx.doi.org/10.1007/s00340-002-0935-3&quot;&gt;https://doi.org/10.1007/s00340-002-0935-3&lt;/a&gt;, 2002.</mixed-citation>
</ref>
<ref id="ref44">
<label>44</label><mixed-citation publication-type="other" xlink:type="simple">Richardson, S. J., Miles, N. L., Davis, K. J., Crosson, E. R., Rella, C. W., and Andrews, A. E.: Field testing of cavity ring-down spectroscopy analyzers measuring carbon dioxide and water vapor, J. Atmos. Oceanic Technol., 29, 397–406, 2012.</mixed-citation>
</ref>
<ref id="ref45">
<label>45</label><mixed-citation publication-type="other" xlink:type="simple">Rigby, M., Prinn, R. G., Fraser, P. J., Simmonds, P. G., Langenfelds, R. L., Huang, J., Cunnold, D. M., Steele, L. P., Krummel, P. B., Weiss, R. F., O&apos;Doherty, S., Salameh, P. K., Wang, H. J., Harth, C. M., Mühle, J., and Porter, L. W.: Renewed growth of atmospheric methane, Geophys. Res. Lett., 35, L22805, &lt;a href=&quot;http://dx.doi.org/10.1029/2008GL036037&quot;&gt;https://doi.org/10.1029/2008GL036037&lt;/a&gt;, 2008.</mixed-citation>
</ref>
<ref id="ref46">
<label>46</label><mixed-citation publication-type="other" xlink:type="simple">Saitoh, N., Imasu, R., Ota, Y., and Niwa, Y.: CO&lt;sub&gt;2&lt;/sub&gt; retrieval algorithm for the thermal infrared spectra of the greenhouse gases observing satellite: Potential of retrieving CO&lt;sub&gt;2&lt;/sub&gt; vertical profile from high-resolution FTS sensor, J. Geophys. Res., 114, D17305, &lt;a href=&quot;http://dx.doi.org/10.1029/2008JD011500&quot;&gt;https://doi.org/10.1029/2008JD011500&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref47">
<label>47</label><mixed-citation publication-type="other" xlink:type="simple">Snover, A., Quay, P. D., and Hao, W. M.: The D/H content of methane emitted from biomass burning, Global Biogeochem. Cy., 14, 11–24, 2000.</mixed-citation>
</ref>
<ref id="ref48">
<label>48</label><mixed-citation publication-type="other" xlink:type="simple">Terao, Y., Mukai, H., Nojiri, Y., Machida, T., Tohjima, Y., Saeki, T., and Maksyutov, S.: Interannual variability and trends in atmospheric methane over the western Pacific from 1994 to 2010, J. Geophys. Res., 116, D14303, &lt;a href=&quot;http://dx.doi.org/10.1029/2010JD015467&quot;&gt;https://doi.org/10.1029/2010JD015467&lt;/a&gt;, 2011.</mixed-citation>
</ref>
<ref id="ref49">
<label>49</label><mixed-citation publication-type="other" xlink:type="simple">Tohjima, Y.: Method for measuring changes in the atmospheric O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; ratio by a gas chromatograph equipped with a thermal conductivity detector, J. Geophys. Res., 105, 14575–14584, 2000.</mixed-citation>
</ref>
<ref id="ref50">
<label>50</label><mixed-citation publication-type="other" xlink:type="simple">Tohjima, Y., Machida, T., Watai, T., Akama, I., Amari, T., and Moriwaki, Y.: Preparation of gravimetric standards for measurements of atmospheric oxygen and reevaluation of atmospheric oxygen concentration, J. Geophys. Res., 110, D11302, &lt;a href=&quot;http://dx.doi.org/10.1029/2004JD005595&quot;&gt;https://doi.org/10.1029/2004JD005595&lt;/a&gt;, 2005.</mixed-citation>
</ref>
<ref id="ref51">
<label>51</label><mixed-citation publication-type="other" xlink:type="simple">Tohjima, Y., Mukai, H., Nojiri, Y., Yamagishi, H., and Machida, T.: Atmospheric O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; measurements at two Japanese sites: estimation of global oceanic and land biotic carbon sinks and analysis of the variations in atmospheric potential oxygen (APO), Tellus, 60B, 213–225, 2008.</mixed-citation>
</ref>
<ref id="ref52">
<label>52</label><mixed-citation publication-type="other" xlink:type="simple">Tohjima, Y., Katsumata, K., Morino, I., Mukai, H., Machida, T., Akama, I., Amari, T., and Tsunogai, U.: Theoretical and experimental evaluation of the isotope effect of NDIR analyzer on atmospheric CO&lt;sub&gt;2&lt;/sub&gt; measurement, J. Geophys. Res., 114, D13302, &lt;a href=&quot;http://dx.doi.org/10.1029/2009JD011734&quot;&gt;https://doi.org/10.1029/2009JD011734&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref53">
<label>53</label><mixed-citation publication-type="other" xlink:type="simple">Varghese, P. and Hanson, R.: Collisional narrowing effects on spectral line shapes measured at high resolution, Appl. Opt., 23, 2376–2385, 1984.</mixed-citation>
</ref>
<ref id="ref54">
<label>54</label><mixed-citation publication-type="other" xlink:type="simple">Winderlich, J., Chen, H., Höfer, A., Gerbig, C., Seifert, T., Kolle, O., Kaiser, C., Lavrič, J. V., and Heimann, M.: Continuous low-maintenance CO&lt;sub&gt;2&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt;/H&lt;sub&gt;2&lt;/sub&gt;O measurements at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia, Atmos. Meas. Tech. Discuss., 3, 1399–1437, &lt;a href=&quot;http://dx.doi.org/10.5194/amtd-3-1399-2010&quot;&gt;https://doi.org/10.5194/amtd-3-1399-2010&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref55">
<label>55</label><mixed-citation publication-type="other" xlink:type="simple">Webster, C. R., May, R. D., Trimble, C. A., Chave, R. G., and Kendall, J.: Aircraft (ER-2) laser infrared absorption spectrometer (ALIAS) for &lt;i&gt;in-situ &lt;/i&gt; stratospheric measurements of HCI, N&lt;sub&gt;2&lt;/sub&gt;O, CH&lt;sub&gt;4&lt;/sub&gt;, NO&lt;sub&gt;2&lt;/sub&gt;, and HNO&lt;sub&gt;3&lt;/sub&gt;, Appl. Opt., 33, 454–472, 1994.</mixed-citation>
</ref>
<ref id="ref56">
<label>56</label><mixed-citation publication-type="other" xlink:type="simple">Webster, C. R., Flesh, G. J., Scott, D. C., Swanson, J. E., May, R. D., Woodward, W. S., Gmachl, C., Capasso, F., Sivco, D. L., Baillargeon, J. N., Hutchinson, A. L., and Cho, A. Y.: Quantum-cascade laser measurements of stratospheric methane and nitrous oxide, Appl. Opt., 40, 321–326, 2001.</mixed-citation>
</ref>
<ref id="ref57">
<label>57</label><mixed-citation publication-type="other" xlink:type="simple">WMO: GAW Report No. 194 – 15th WMO/IAEA Meeting if Experts on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques, Tech. Rep., World Meteorological Organization, 2009.</mixed-citation>
</ref>
<ref id="ref58">
<label>58</label><mixed-citation publication-type="other" xlink:type="simple">Wunch, D., Toon, G. C., Blavier, J.-F., Washenfelder, R. A., Notholt, J., Connor, B. J., Griffith, D. W. T., Sherlock, V., and Wennberg, P. O.: The total carbon column observing network, Phil. Trans. Roy. Soc. A, 369, 2087–2112, &lt;a href=&quot;http://dx.doi.org/10.1098/rsta.2010.0240&quot;&gt;https://doi.org/10.1098/rsta.2010.0240&lt;/a&gt;, 2012.</mixed-citation>
</ref>
<ref id="ref59">
<label>59</label><mixed-citation publication-type="other" xlink:type="simple">Xiong, X., Barnet, C. D., Zhuang, Q., Machida, T., Sweeney, C., and Patra, P. K.: Mid-upper tropospheric methane in the high northern hemisphere: Spaceborne observations by AIRS, aircraft measurements, and model simulations, J. Geophys. Res., 115, D19309, &lt;a href=&quot;http://dx.doi.org/10.1029/2009JD013796&quot;&gt;https://doi.org/10.1029/2009JD013796&lt;/a&gt;, 2010.</mixed-citation>
</ref>
<ref id="ref60">
<label>60</label><mixed-citation publication-type="other" xlink:type="simple">Yokota, T., Yoshida, Y., Eguchi, N., Ota, Y., Tanaka, T., Watanabe, H., and Maksyutov, S.: Global concentrations of CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; retrieved from GOSAT: First preliminary results, SOLA, 5, 160–163, &lt;a href=&quot;http://dx.doi.org/10.2151/sola.2009-041&quot;&gt;https://doi.org/10.2151/sola.2009-041&lt;/a&gt;, 2009.</mixed-citation>
</ref>
<ref id="ref61">
<label>61</label><mixed-citation publication-type="other" xlink:type="simple">Yoshida, Y., Ota, Y., Eguchi, N., Kikuchi, N., Nobuta, K., Tran, H., Morino, I., and Yokota, T.: Retrieval algorithm for CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; column abundances from short-wavelength infrared spectral observations by the Greenhouse gases observing satellite, Atmos. Meas. Tech., 4, 717–734, &lt;a href=&quot;http://dx.doi.org/10.5194/amt-4-717-2011&quot;&gt;https://doi.org/10.5194/amt-4-717-2011&lt;/a&gt;, 2011.</mixed-citation>
</ref>
</ref-list>
</back>
</article>