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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-11-8207-2011</article-id>
<title-group>
<article-title>A new method to detect long term trends of methane (CH&lt;sub&gt;4&lt;/sub&gt;) and nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) total columns measured within the NDACC ground-based high resolution solar FTIR network</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Angelbratt</surname>
<given-names>J.</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>Mellqvist</surname>
<given-names>J.</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>Blumenstock</surname>
<given-names>T.</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>Borsdorff</surname>
<given-names>T.</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>Brohede</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>Duchatelet</surname>
<given-names>P.</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>Forster</surname>
<given-names>F.</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>Hase</surname>
<given-names>F.</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>Mahieu</surname>
<given-names>E.</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>Murtagh</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>Petersen</surname>
<given-names>K.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Schneider</surname>
<given-names>M.</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>Sussmann</surname>
<given-names>R.</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>Urban</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Chalmers University of Technology, Göteborg, Sweden</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Institute of Astrophysics and Geophysics, University of Liège, Liège, Belgium</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Institute of Environmental Physics, University of Bremen, Bremen, Germany</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Garmisch-Partenkirchen, Germany</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>10</day>
<month>03</month>
<year>2011</year>
</pub-date>
<volume>11</volume>
<issue>3</issue>
<fpage>8207</fpage>
<lpage>8247</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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<self-uri xlink:href="http://www.atmos-chem-phys-discuss.net/11/8207/2011/acpd-11-8207-2011.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/8207/2011/acpd-11-8207-2011.pdf</self-uri>
<abstract>
<p>A multiple regression model has been used to estimate linear trends of the
CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O total columns measured with the ground-based solar
FTIR technique at four European stations, i.e. Jungfraujoch (47&amp;deg; N, 8&amp;deg; E, 3600 m a.s.l.), Zugspitze (47&amp;deg; N, 11&amp;deg; E, 3000 m a.s.l.),
 Harestua (60&amp;deg; N, 11&amp;deg; E, 600 m a.s.l.) and Kiruna (68&amp;deg; N, 20&amp;deg; E, 400 m a.s.l.).
  The total columns were retrieved with a common method developed
within the EU-project HYMN. Anomalies from air pressure, total columns of
hydrogen fluoride (HF) and carbon monoxide (CO) and tropopause height were
used in the regression model to reduce the time series variability and
thereby estimate trustful trends. Significant positive CH&lt;sub&gt;4&lt;/sub&gt; trends of
0.13–0.25% yr&lt;sup&gt;&amp;minus;1&lt;/sup&gt; at the 2-&amp;sigma; level were found for all
participating stations for the 1996–2009 period. The strongest trends were
estimated at northern latitudes stations while slightly weaker trends were
observed in the Alps. For the time period of 2007–2009 a strong increase in
the CH&lt;sub&gt;4&lt;/sub&gt; total column was observed for all stations with the strongest
yearly growth at Kiruna (1.15 &amp;plusmn; 0.17% yr&lt;sup&gt;&amp;minus;1&lt;/sup&gt;). Significant positive
N&lt;sub&gt;2&lt;/sub&gt;O trends of 0.19–0.40% yr&lt;sup&gt;&amp;minus;1&lt;/sup&gt; were found for all stations in the
1996–2007 period with the strongest trend at Harestua. From the N&lt;sub&gt;2&lt;/sub&gt;O
data also crude tropospheric and stratospheric partial columns were derived,
indicating that the observed difference in the N&lt;sub&gt;2&lt;/sub&gt;O trends between the
FTIR sites is of stratospheric origin. This agrees well with the N&lt;sub&gt;2&lt;/sub&gt;O
measurements by the Odin/SMR satellite showing the highest trends at
Harestua 0.98 &amp;plusmn; 0.28% yr&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, and considerably smaller trends in the
alp regions 0.27 &amp;plusmn; 0.25% yr&lt;sup&gt;&amp;minus;1&lt;/sup&gt;. The multiple regression model was
compared with two other trend methods, the ordinary linear regression and a
Bootstrap algorithm. The multiple regression model estimated CH&lt;sub&gt;4&lt;/sub&gt; and
N&lt;sub&gt;2&lt;/sub&gt;O trends that differed by 12–31% compared to the other two
methods. Since the trends estimated with the multiple regression model were
carefully validated this stresses the importance to account for the
atmospheric variability when estimating trends of CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O
total columns.</p>
</abstract>
<counts><page-count count="41"/></counts>
</article-meta>
</front>
<body/>
<back>
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