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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-9-2223-2009</article-id>
<title-group>
<article-title>Forecasted deep stratospheric intrusions over Central Europe: case studies and climatologies</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Trickl</surname>
<given-names>T.</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>Feldmann</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kanter</surname>
<given-names>H.-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>Scheel</surname>
<given-names>H.-E.</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>Sprenger</surname>
<given-names>M.</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>Stohl</surname>
<given-names>A.</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>Wernli</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Rheinisches Institut für Umweltforschung, Univ. zu Köln, Aachener Str. 201–209, 50931 Köln, Germany</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Eidgenössische Technische Hochschule (ETH) Zürich, Institut für Atmosphäre und Klima, Universitätstr. 16, 8092 Zürich, Switzerland</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Norwegian Institute for Air Research, P.O. Box 100, Instituttveien 18, 2027 Kjeller, Norway</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>now at: Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung (IMK-TRO), Postfach 3640, 76021 Karlsruhe, Germany</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>now at: Johannes-Gutenberg-Universität Mainz, Institut für Physik der Atmosphäre, 55099 Mainz, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>26</day>
<month>01</month>
<year>2009</year>
</pub-date>
<volume>9</volume>
<issue>1</issue>
<fpage>2223</fpage>
<lpage>2288</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>Based on daily predictions of stratospheric air intrusions, obtained from
trajectory calculations by ETH Zürich with wind fields from ECMWF
forecasts, a high number of measurements with the ozone lidar at IMK-IFU
(Garmisch-Partenkirchen, Germany) were carried out in 2001. The lidar
measurements show a large variety of rather different cases. In part,
tropopause folds could be fully captured. The frequency of intrusion cases
forecasted and verified by vertical sounding or in the in-situ data
recorded at the nearby Zugspitze summit (2962 m a.s.l.) exceed that in
previous work by more than a factor of two. Three cases mapped with the lidar
were selected to validate the results for the corresponding time periods
extracted from a one-year run with the new hemispheric version of the
chemistry-transport model EURAD. Due to the high spatial resolution chosen
for these simulations the agreement with the lidar measurements is
satisfactory. The Zugspitze ozone data from 1978 to 2004 were recently
filtered by applying different criteria for stratospheric air, based on the
&lt;sup&gt;7&lt;/sup&gt;Be and humidity measurements. Here, by using the daily model forecasts
during the time period 2001–2005, we examine three criteria and determine
how well they represent the stratospheric air intrusions reaching the
mountain site. Seasonal cycles for the period 2001–2005 were derived for the
forecasts as well as the intrusion frequency per month for the forecasted
intrusions and each of the criteria, distinguishing eight different
characteristic transport pathways. In most cases a winter maximum and a
summer minimum was obtained, but in the case of cyclonic arrival of
intrusions starting over Greenland a late-spring maximum is seen. Two of the
filtering criteria examined, based on combining a relative-humidity (RH)
threshold of 60% with either a &lt;sup&gt;7&lt;/sup&gt;Be threshold of 5.5 mBq m&lt;sup&gt;&amp;minus;3&lt;/sup&gt; or
the requirement for RH &amp;le;30% within &amp;plusmn;6 h, rather reliably predict
periods of deep intrusions reaching the Zugspitze station. An &quot;or&quot;
combination of both these criteria yields slightly more cases and covers
77.9% of the intrusions identified. The lack of observations in the
complementary 22.1% are mostly explained by overpasses. In this way the
long-term trend of stratospheric ozone observed at this site as well as the
corresponding ozone budget may be derived on the basis of measurements only.
This effort will be the subject of a subsequent publication.</p>
</abstract>
<counts><page-count count="66"/></counts>
</article-meta>
</front>
<body/>
<back>
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