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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACPD</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics Discussions</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACPD</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7375</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/acpd-10-4143-2010</article-id>
<title-group>
<article-title>Impacts of HONO sources on the photochemistry in Mexico City during  the MCMA-2006/MILAGO Campaign</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Li</surname>
<given-names>G.</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>Lei</surname>
<given-names>W.</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>Zavala</surname>
<given-names>M.</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>Volkamer</surname>
<given-names>R.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Dusanter</surname>
<given-names>S.</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>Stevens</surname>
<given-names>P.</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>Molina</surname>
<given-names>L. T.</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-group><aff id="aff1">
<label>1</label>
<addr-line>Molina Center for the Energy and the Environment, La Jolla, CA 92037,  USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Massachusetts Institute of Technology, Cambridge, MA 02139, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Chemistry, University of Colorado at Boulder, 215 UCB,  Boulder, CO 80309, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Cooperative Institute for Research in the Environmental Sciences (CIRES),  University of Colorado at Boulder, 216 UCB, Boulder, CO 80309, USA</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Center for Research in Environmental Science, School of Public and  Environmental Affairs, and Department of Chemistry, Indiana University,  Bloomington, IN 47405, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>11</day>
<month>02</month>
<year>2010</year>
</pub-date>
<volume>10</volume>
<issue>2</issue>
<fpage>4143</fpage>
<lpage>4188</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>
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<abstract>
<p>The contribution of HONO sources to the photochemistry in Mexico City
      is investigated during the MCMA-2006/MILAGO Campaign using the
      WRF-CHEM model. Besides the homogeneous reaction of NO with OH, four
      additional HONO sources are considered in the WRF-CHEM model:
      secondary HONO formation from NO&lt;sub&gt;2&lt;/sub&gt; heterogeneous reaction
      with semivolatile organics, NO&lt;sub&gt;2&lt;/sub&gt; reaction with freshly
      emitted soot, NO&lt;sub&gt;2&lt;/sub&gt; heterogeneous reaction on aerosol and
      ground surfaces. The WRF-CHEM model with the five HONO sources
      performs reasonably well in tracking the observed diurnal variation of
      HONO concentrations. The HONO sources included are found to
      significantly improve the HO&lt;sub&gt;x&lt;/sub&gt; (OH+HO&lt;sub&gt;2&lt;/sub&gt;) simulations
      during daytime and the partition of NO/NO&lt;sub&gt;2&lt;/sub&gt; in the
      morning. The HONO sources also accelerate the accumulation of O&lt;sub&gt;3&lt;/sub&gt;
      concentrations in the morning by about 2 h and subsequently result in
      a noticeable enhancement of O&lt;sub&gt;3&lt;/sub&gt; concentrations over the course of
      the day with a midday average of about 6 ppb. Furthermore, these HONO
      sources play a very important role in the formation of secondary
      aerosols in the morning. They substantially enhance the secondary
      organic aerosol concentrations by a factor of 2 on average in the
      morning, although contribute less during the rest of the day. The
      simulated nitrate and ammonium aerosols are also remarkably enhanced
      in the morning when the four HONO sources are added, in good agreement
      with the measurements. The impact of the HONO sources on the sulfate
      aerosols is negligible because of the inefficient conversion of
      H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; from SO&lt;sub&gt;2&lt;/sub&gt; reacting with OH.</p>
</abstract>
<counts><page-count count="46"/></counts>
</article-meta>
</front>
<body/>
<back>
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