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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-9-11333-2009</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/9/11333/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/9/11333/2009/acpd-9-11333-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/9/11333/2009/acpd-9-11333-2009.pdf</fulltext_pdf>
	<start_page>11333</start_page>
	<end_page>11366</end_page>
	<publication_date>2009-05-06</publication_date>
	<article_title content_type="html">Microphysical and optical properties of Arctic mixed-phase clouds â€“ the 9 April 2007 case study</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>J.-F. Gayet</name>
			<email>gayet@opgc.univ-bpclermont.fr</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>G. Mioche</name>
		</author>
		<author numeration="3" affiliations="2">
			<name>A. DÃ¶rnbrack</name>
		</author>
		<author numeration="4" affiliations="3,5">
			<name>A. Ehrlich</name>
		</author>
		<author numeration="5" affiliations="4">
			<name>A. Lampert</name>
		</author>
		<author numeration="6" affiliations="3,5">
			<name>M. Wendisch</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Laboratoire de MÃ©tÃ©orologie Physique, UniversitÃ© Blaise Pascal, Clermont-Ferrand, France</affiliation>
		<affiliation numeration="2" content_type="html">Institute for Atmospheric Physics, DLR Oberpfaffenhofen, Wessling, Germany</affiliation>
		<affiliation numeration="3" content_type="html">Johannes Gutenberg University, Institute for Atmospheric Physics, Mainz, Germany</affiliation>
		<affiliation numeration="4" content_type="html">Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany</affiliation>
		<affiliation numeration="5" content_type="html">now at: University of Leipzig, Leipzig Institute for Meteorology (LIM), Leipzig, Germany</affiliation>
	</affiliations>
	<abstract content_type="html">Airborne measurements in Arctic boundary-layer stratocumulus were
carried out near Spitsbergen on 9 April 2007 during the Arctic Study of
Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign. A unique set of
co-located observations is used to describe the cloud properties, including
detailed in situ cloud microphysical and radiation measurements along with
airborne and co-located spaceborne remote sensing data (Lidar on
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations [CALIPSO]
and radar on CloudSat satellites). The CALIPSO profiles evidence a cloud top
temperature which varies between &amp;minus;24&amp;deg;C and &amp;minus;21&amp;deg;C. The in situ cloud
observations reveal that the attenuated backscatter signal from lidar along
the aircraft trajectory is linked with the presence of liquid water and
therefore confirms a cloud top layer dominated by liquid-water, which is a
common feature observed in Arctic mixed-phase stratocumulus clouds. A low
concentration of quite large ice crystals are also evidenced up to the cloud
top and lead to significant CloudSat radar echo. Since the ratio of the
extinction of liquid water droplets and ice crystals is high the broadband
radiative effects near the cloud top are mostly dominated by water droplets.
CloudSat observations as well as in situ measurements reveal high
reflectivity factors (up to 15 dBZ) and precipitation rates (1 mm h&lt;sup&gt;&amp;minus;1&lt;/sup&gt;).
This feature is due to efficient ice production processes. About 25% of
the theoretically available liquid water is converted into ice water with
large ice crystals which precipitate. According to an estimation of the mean
cloud cover, a considerable value of 10&lt;sup&gt;6&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt; of fresh
water could be settled over the Greenland sea pool. European Centre for
Medium-Range Weather Forecast (ECMWF) operational analyses reproduces the
variation of the boundary layer height along the flight track. However,
small-scale features in the observed cloud field cannot be resolved by ECMWF
analysis. Furthermore, ECMWF&apos;s diagnostic partitioning of the condensed
water into ice and liquid reveals serious shortcomings for Arctic
mixed-phased clouds. Too much ice is modeled.</abstract>
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