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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus GmbH</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-11-705-2011</article-id>
<title-group>
<article-title>Assessment of fossil fuel carbon dioxide and other anthropogenic trace gas emissions from airborne measurements over Sacramento, California in spring 2009</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Turnbull</surname>
<given-names>J. C.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Karion</surname>
<given-names>A.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fischer</surname>
<given-names>M. L.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Faloona</surname>
<given-names>I.</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Guilderson</surname>
<given-names>T.</given-names>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Lehman</surname>
<given-names>S. J.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Miller</surname>
<given-names>B. R.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Miller</surname>
<given-names>J. B.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Montzka</surname>
<given-names>S.</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>Sherwood</surname>
<given-names>T.</given-names>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Saripalli</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Sweeney</surname>
<given-names>C.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tans</surname>
<given-names>P. P.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>National Oceanic and Atmospheric Administration, Earth Systems Research Laboratory, 325 Broadway, Boulder, CO 80305, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Institute of Alpine and Arctic Research, University of Colorado at Boulder, Boulder, CO 80309-0450, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO 80309-0216, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Dept. of Land, Air and Water Resources, University of California, Davis, CA 95616-8627, USA</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>Lawrence Livermore National Laboratories, Center for Accelerator Mass Spectrometry, Livermore, CA 94551, USA</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>KalScott Engineering, 811 E 28th St, Lawrence, KS 66046, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>25</day>
<month>01</month>
<year>2011</year>
</pub-date>
<volume>11</volume>
<issue>2</issue>
<fpage>705</fpage>
<lpage>721</lpage>
<permissions>
<license xlink:type="simple">
<license-p>This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
</license>
</permissions>
<self-uri xlink:href="http://www.atmos-chem-phys.net/11/705/2011/acp-11-705-2011.html">This article is available from http://www.atmos-chem-phys.net/11/705/2011/acp-11-705-2011.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/11/705/2011/acp-11-705-2011.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/705/2011/acp-11-705-2011.pdf</self-uri>
<abstract>
<p>Direct quantification of fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; (CO&lt;sub&gt;2&lt;/sub&gt;ff) in atmospheric
samples can be used to examine several carbon cycle and air quality
questions. We collected in situ CO&lt;sub&gt;2&lt;/sub&gt;, CO, and CH&lt;sub&gt;4&lt;/sub&gt; measurements and
flask samples in the boundary layer and free troposphere over Sacramento,
California, USA, during two aircraft flights over and downwind of this urban
area during spring of 2009. The flask samples were analyzed for &amp;Delta;&lt;sup&gt;14&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; to determine the recently added CO&lt;sub&gt;2&lt;/sub&gt;ff
mole fraction. A suite of greenhouse and other trace gases, including
hydrocarbons and halocarbons, were measured in the same samples. Strong
correlations were observed between CO&lt;sub&gt;2&lt;/sub&gt;ff and numerous trace gases
associated with urban emissions. From these correlations we estimate
emission ratios between CO&lt;sub&gt;2&lt;/sub&gt;ff and these species, and compare these with
bottom-up inventory-derived estimates. Recent county level inventory
estimates for carbon monoxide (CO) and benzene from the California Air
Resources Board CEPAM database are in good agreement with our measured
emission ratios, whereas older emissions inventories appear to overestimate
emissions of these gases by a factor of two. For most other trace species,
there are substantial differences (200–500%) between our measured
emission ratios and those derived from available emission inventories. For
the first flight, we combine in situ CO measurements with the measured
CO:CO&lt;sub&gt;2&lt;/sub&gt;ff emission ratio of 14 &amp;plusmn; 2 ppbCO/ppmCO&lt;sub&gt;2&lt;/sub&gt; to derive an
estimate of CO&lt;sub&gt;2&lt;/sub&gt;ff mole fraction throughout this flight, and also
estimate the biospheric CO&lt;sub&gt;2&lt;/sub&gt; mixing ratio (CO&lt;sub&gt;2&lt;/sub&gt;bio) from the
difference of total and fossil CO&lt;sub&gt;2&lt;/sub&gt;. The resulting CO&lt;sub&gt;2&lt;/sub&gt;bio varies
dramatically from up to 8 &amp;plusmn; 2 ppm in the urban plume to −6 &amp;plusmn; 1 ppm in
the surrounding boundary layer air. Finally, we use the in situ estimates of
CO&lt;sub&gt;2&lt;/sub&gt;ff mole fraction to infer total fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; emissions from
the Sacramento region, using a mass balance approach. The resulting
emissions are uncertain to within a factor of two due to uncertainties in
wind speed and boundary layer height. Nevertheless, this first attempt to
estimate urban-scale CO&lt;sub&gt;2&lt;/sub&gt;ff from atmospheric radiocarbon measurements
shows that CO&lt;sub&gt;2&lt;/sub&gt;ff can be used to verify and improve emission inventories
for many poorly known anthropogenic species, separate biospheric CO&lt;sub&gt;2&lt;/sub&gt;,
and indicates the potential to constrain CO&lt;sub&gt;2&lt;/sub&gt;ff emissions if transport
uncertainties are reduced.</p>
</abstract>
<counts><page-count count="17"/></counts>
</article-meta>
</front>
<body/>
<back>
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