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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics Discussions</journal_title>
		<journal_url>www.atmos-chem-phys-discuss.net</journal_url>
		<issn>1680-7367</issn>
		<eissn>1680-7375</eissn>
		<volume_number>7</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2007</publication_year>
	</journal>
	<doi>10.5194/acpd-7-2531-2007</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/7/2531/2007/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/7/2531/2007/acpd-7-2531-2007.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/7/2531/2007/acpd-7-2531-2007.pdf</fulltext_pdf>
	<start_page>2531</start_page>
	<end_page>2560</end_page>
	<publication_date>2007-02-21</publication_date>
	<article_title content_type="html">Aircraft pollution: a futuristic view</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>O. A. SÃ¸vde</name>
			<email>asovde@geo.uio.no</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>M. Gauss</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>I. S. A. Isaksen</name>
		</author>
		<author numeration="4" affiliations="2">
			<name>G. Pitari</name>
		</author>
		<author numeration="5" affiliations="3">
			<name>C. Marizy</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Department of Geosciences, University of Oslo, Norway</affiliation>
		<affiliation numeration="2" content_type="html">Dipartimento di Fisica, University of L&apos;Aquila, Italy</affiliation>
		<affiliation numeration="3" content_type="html">Airbus France,  Acoustics &amp; Environment Departmemt, Toulouse, France</affiliation>
	</affiliations>
	<abstract content_type="html">Impacts of NO&lt;sub&gt;x&lt;/sub&gt;, H&lt;sub&gt;2&lt;/sub&gt;O and aerosol emissions from a projected
2050 aircraft fleet, provided in the EU project SCENIC, are
investigated using the Oslo CTM2, a 3-D chemical transport model
including comprehensive chemistry for the stratosphere and the
troposphere.
The aircraft emission scenarios comprise emissions from subsonic and
supersonic aircraft.
The increases in NO&lt;sub&gt;y&lt;/sub&gt; due to emissions from the mixed fleet are
comparable for subsonic (at 11&amp;ndash;12 km) and supersonic (at 18&amp;ndash;20 km)
aircraft, with annual zonal means of 1.35 ppbv and 0.83 ppbv,
respectively. H&lt;sub&gt;2&lt;/sub&gt;O increases are also comparable at these altitudes:
630 and 599 ppbv, respectively.
The aircraft emissions increase tropospheric ozone by about 10 ppbv in
the Northern Hemisphere due to increased ozone production, mainly
because of subsonic aircraft.
Supersonic aircraft contribute to a reduction of stratospheric ozone
due to increased ozone loss at higher altitudes.
In the Northern Hemisphere the reduction is about 39 ppbv, but also in
the Southern Hemisphere a 22 ppbv stratospheric decrease is modeled due to
transport of supersonic aircraft emissions and ozone depleted air.
The total ozone column is increased in lower and Northern
mid-latitudes, otherwise the increase of ozone loss contributes
to a decrease of the total ozone column. Two exceptions are the
Northern Hemispheric spring, where the ozone loss increase is small
due to transport processes, and tropical latitudes during summer where
the effect of subsonic aircraft is low due to a high tropopause.
Aerosol particles emitted by aircraft reduce both aircraft and
background NO&lt;sub&gt;x&lt;/sub&gt;, more than counterweighting the effect of
NO&lt;sub&gt;x&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O aircraft emissions in the stratosphere.
Above about 20 km altitude, the NO&lt;sub&gt;x&lt;/sub&gt; (and thus ozone loss) reduction
is large enough to give an increase in ozone due to aircraft
emissions. This effect is comparable in the Northern and Southern
Hemisphere.
At 11&amp;ndash;20 km altitude, however, ozone production is reduced due to
less NO&lt;sub&gt;x&lt;/sub&gt;. Also ClONO&lt;sub&gt;2&lt;/sub&gt; is increased at this altitude due to
enhanced heterogeneous reactions (lowered HCl), and ClO is increased
due to less NO&lt;sub&gt;x&lt;/sub&gt;, further enhancing ozone loss in this region. This
results in a 14 ppbv further reduction of ozone.
Mainly, this results in an increase of the total ozone column due to
a decrease in ozone loss caused by the NO&lt;sub&gt;x&lt;/sub&gt; cycle (at the highest
altitudes). At the lowermost latitudes, the reduced loss due to the
NO&lt;sub&gt;x&lt;/sub&gt; cycle is small. However, ozone production at lower altitudes is
reduced and the loss due to ClO is increased, giving a decrease in the
total ozone column.
Also, at high latitudes during spring the heterogeneous chemistry is
more efficient on PSCs, increasing the ozone loss.</abstract>
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</article>

