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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>9</volume_number>
		<issue_number>3</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acpd-9-13593-2009</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/9/13593/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/9/13593/2009/acpd-9-13593-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/9/13593/2009/acpd-9-13593-2009.pdf</fulltext_pdf>
	<start_page>13593</start_page>
	<end_page>13628</end_page>
	<publication_date>2009-06-19</publication_date>
	<article_title content_type="html">The continental source of glyoxal estimated by the synergistic use of spaceborne measurements and inverse modelling</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>T. Stavrakou</name>
			<email>jenny@aeronomie.be</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>J.-F. MÃ¼ller</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>I. De Smedt</name>
		</author>
		<author numeration="4" affiliations="1">
			<name>M. Van Roozendael</name>
		</author>
		<author numeration="5" affiliations="2">
			<name>M. Kanakidou</name>
		</author>
		<author numeration="6" affiliations="3">
			<name>M. Vrekoussis</name>
		</author>
		<author numeration="7" affiliations="3">
			<name>F. Wittrock</name>
		</author>
		<author numeration="8" affiliations="3">
			<name>A. Richter</name>
		</author>
		<author numeration="9" affiliations="3,4">
			<name>J. P. Burrows</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Belgian Institute for Space Aeronomy, Avenue Circulaire 3, 1180, Brussels, Belgium</affiliation>
		<affiliation numeration="2" content_type="html">ECPL, Department of Chemistry, University of Crete, Heraklion, Greece</affiliation>
		<affiliation numeration="3" content_type="html">Institute of Environmental Physics, University of Bremen, Bremen, Germany</affiliation>
		<affiliation numeration="4" content_type="html">Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK</affiliation>
	</affiliations>
	<abstract content_type="html">Tropospheric glyoxal and formaldehyde columns retrieved from the SCIAMACHY
satellite instrument in 2005 are used with the IMAGESv2 global
chemistry-transport model and its adjoint in a two-compound inversion scheme
designed to estimate the continental source of glyoxal. The formaldehyde
observations provide an important constraint on the production of glyoxal
from isoprene in the model, since the degradation of isoprene constitutes an
important source of both glyoxal and formaldehyde. Current modelling studies
underestimate largely the observed glyoxal satellite columns, pointing to the
existence of an additional land glyoxal source of biogenic origin. We include
an extra glyoxal source in the model and we explore its possible distribution
and magnitude through two inversion experiments. In the first case, the
additional source is represented as a direct glyoxal emission, and in the
second, as a secondary formation through the oxidation of an unspecified
glyoxal precursor. Besides this extra source, the inversion scheme optimizes
the primary glyoxal and formaldehyde emissions, as well as their secondary
production from other identified non-methane volatile organic precursors of
anthropogenic, pyrogenic and biogenic origin.
&lt;br&gt;&lt;br&gt;
In the first inversion experiment, the additional direct source, estimated at
36 Tg/yr, represents 38% of the global continental source, whereas the
contribution of isoprene is equally important (30%), the remainder being
accounted for by anthropogenic (20%) and pyrogenic fluxes. The inversion
succeeds in reducing the underestimation of the glyoxal columns by the model,
but it leads to a severe overestimation of glyoxal surface concentrations in
comparison with in situ measurements. In the second scenario, the inferred
total global continental glyoxal source is estimated at 108 Tg/yr, almost
two times higher than the global a priori source. The extra secondary source
is the largest contribution to the global glyoxal budget (50%), followed by
the production from isoprene (26%) and from anthropogenic NMVOC precursors
(14%). A better performance is achieved in this case, as the updated
emissions allow for a satisfactory agreement of the model with both satellite
and in situ glyoxal observations.</abstract>
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