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<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-11-3211-2011</article-id>
<title-group>
<article-title>African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; mediated smoke particle activation</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fiedler</surname>
<given-names>V.</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>Arnold</surname>
<given-names>F.</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>Ludmann</surname>
<given-names>S.</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>Minikin</surname>
<given-names>A.</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>Hamburger</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>Pirjola</surname>
<given-names>L.</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>Dörnbrack</surname>
<given-names>A.</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>Schlager</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234 Wessling,  Germany</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Max-Planck Institute for Nuclear Physics, (MPIK), Atmospheric Physics Division, P.O. Box 103980, 69029  Heidelberg, Germany</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Technology, Metropolia University of Applied Sciences, P.O. Box 4000, 00180 Helsinki, Finland</addr-line>
</aff>
<pub-date pub-type="epub">
<day>05</day>
<month>04</month>
<year>2011</year>
</pub-date>
<volume>11</volume>
<issue>7</issue>
<fpage>3211</fpage>
<lpage>3225</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.net/11/3211/2011/acp-11-3211-2011.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/3211/2011/acp-11-3211-2011.pdf</self-uri>
<abstract>
<p>Airborne measurements of trace gases and aerosol particles have been made in
two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea).
The plumes originated from BB in the Southern-Hemisphere African savanna
belt. On the day of our measurements (13 August 2006), the plumes had ages of
about 10 days and were respectively located in the middle troposphere (MT) at
3900–5500 m altitude and in the upper troposphere (UT) at 10 800–11 200 m.
Probably, the MT plume was lifted by dry convection and the UT plume was
lifted by wet convection. In the more polluted MT-plume, numerous measured
trace species had markedly elevated abundances, particularly SO&lt;sub&gt;2&lt;/sub&gt; (up
to 1400 pmol mol&lt;sup&gt;−1&lt;/sup&gt;), HNO&lt;sub&gt;3&lt;/sub&gt; (5000–8000 pmol mol&lt;sup&gt;−1&lt;/sup&gt;) and smoke particles with
diameters larger than 270 nm (up to 2000 cm&lt;sup&gt;&amp;minus;3&lt;/sup&gt;). Our MT-plume measurements
indicate that SO&lt;sub&gt;2&lt;/sub&gt; released by BB had not experienced significant loss
by deposition and cloud processes but rather had experienced OH-induced
conversion to gas-phase sulfuric acid. By contrast, a significant fraction of
the released NO&lt;sub&gt;y&lt;/sub&gt; had experienced loss, most likely as HNO&lt;sub&gt;3&lt;/sub&gt; by
deposition. In the UT-plume, loss of NO&lt;sub&gt;y&lt;/sub&gt; and SO&lt;sub&gt;2&lt;/sub&gt; was more
pronounced compared to the MT-plume, probably due to cloud processes.
Building on our measurements and accompanying model simulations, we have
investigated trace gas transformations in the ageing and diluting plumes and
their role in smoke particle processing and activation. Emphasis was placed
upon the formation of sulfuric acid and ammonium nitrate, and their influence
on the activation potential of smoke particles. Our model simulations reveal
that, after 13 August, the lower plume traveled across the Atlantic and
descended to 1300 m and hereafter ascended again. During the travel across
the Atlantic, the soluble mass fraction of smoke particles and their mean
diameter increased sufficiently to allow the processed smoke particles to act
as water vapor condensation nuclei already at very low water vapor
supersaturations of only about 0.04%. Thereby, aged smoke particles had
developed a potential to act as water vapor condensation nuclei in the
formation of maritime clouds.</p>
</abstract>
<counts><page-count count="15"/></counts>
</article-meta>
</front>
<body/>
<back>
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