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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-2-401-2009</article-id>
<title-group>
<article-title>An improved tropospheric NO&lt;sub&gt;2&lt;/sub&gt; retrieval for OMI observations in the vicinity of mountainous terrain</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Zhou</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>Brunner</surname>
<given-names>D.</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>Boersma</surname>
<given-names>K. F.</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>Dirksen</surname>
<given-names>R.</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>Wang</surname>
<given-names>P.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Empa, Swiss Federal Lab. for Materials Testing and Research, Dübendorf, Switzerland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Royal Netherlands Meteorological Institute, KNMI, De Bilt, The Netherlands</addr-line>
</aff>
<pub-date pub-type="epub">
<day>29</day>
<month>07</month>
<year>2009</year>
</pub-date>
<volume>2</volume>
<issue>2</issue>
<fpage>401</fpage>
<lpage>416</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2009 Y. Zhou et al.</copyright-statement>
<copyright-year>2009</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/2/401/2009/amt-2-401-2009.html">This article is available from https://amt.copernicus.org/articles/2/401/2009/amt-2-401-2009.html</self-uri>
<self-uri xlink:href="https://amt.copernicus.org/articles/2/401/2009/amt-2-401-2009.pdf">The full text article is available as a PDF file from https://amt.copernicus.org/articles/2/401/2009/amt-2-401-2009.pdf</self-uri>
<abstract>
<p>We present an approach to reduce topography-related errors of vertical
tropospheric columns (VTC) of NO&lt;sub&gt;2&lt;/sub&gt; retrieved from the Ozone Monitoring
Instrument (OMI) in the vicinity of mountainous terrain. This is crucial for
reliable estimates of air pollution levels over our particular area of
interest, the Alpine region and the adjacent planes, where the Dutch OMI
NO&lt;sub&gt;2&lt;/sub&gt; product (DOMINO) exhibits significant biases due to the coarse
resolution of surface parameters used in the retrieval. Our approach replaces
the coarse-gridded surface pressures by accurate pixel-average values using a
high-resolution topography data set, and scales the a priori NO&lt;sub&gt;2&lt;/sub&gt; profiles
accordingly. NO&lt;sub&gt;2&lt;/sub&gt; VTC reprocessed in this way for the period 2006–2007
suggest that NO&lt;sub&gt;2&lt;/sub&gt; over the Po Valley in Italy and over the Swiss plateau is
underestimated by DOMINO by about 15–20% in winter and 5% in summer under
clear-sky conditions (cloud radiance fraction &amp;lt;0.5). A sensitivity analysis
shows that these seasonal differences are mainly due to the different a
priori NO&lt;sub&gt;2&lt;/sub&gt; profile shapes and solar zenith angles in winter and summer.
The comparison of NO&lt;sub&gt;2&lt;/sub&gt; columns from the original and the enhanced retrieval
with corresponding columns deduced from ground-based in situ observations
over the Swiss Plateau and the Po Valley illustrates the promise of our new
retrieval. It partially reduces the underestimation of the OMI VTCs at
polluted sites in winter and fall and generally improves the agreement in
terms of slope and correlation at rural stations. It does not solve, however,
the issue that the OMI DOMINO product tends to overestimate very low columns
observed at rural sites in spring and summer.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
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