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<article language="en">
	<journal>
		<journal_title>The Cryosphere Discussions</journal_title>
		<journal_url>www.the-cryosphere-discuss.net</journal_url>
		<issn>1994-0432</issn>
		<eissn>1994-0440</eissn>
		<volume_number>4</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2010</publication_year>
	</journal>
	<doi>10.5194/tcd-4-31-2010</doi>
	<article_url>http://www.the-cryosphere-discuss.net/4/31/2010/</article_url>
	<abstract_html>http://www.the-cryosphere-discuss.net/4/31/2010/tcd-4-31-2010.html</abstract_html>
	<fulltext_pdf>http://www.the-cryosphere-discuss.net/4/31/2010/tcd-4-31-2010.pdf</fulltext_pdf>
	<start_page>31</start_page>
	<end_page>75</end_page>
	<publication_date>2010-01-14</publication_date>
	<article_title content_type="html">Monitoring ice shelf velocities from repeat MODIS and Landsat data – a method study on the Larsen C ice shelf, Antarctic Peninsula, and 10 other ice shelves around Antarctica</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>T. Haug</name>
			<email>torborg.haug@geo.uio.no</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>A. Kääb</name>
		</author>
		<author numeration="3" affiliations="2">
			<name>P. Skvarca</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, 0316 Oslo, Norway</affiliation>
		<affiliation numeration="2" content_type="html">Instituto Antártico Argentino, Cerrito 1248, C1010AAZ Buenos Aires, Argentina</affiliation>
	</affiliations>
	<abstract content_type="html">We investigate the velocity field of the Larsen C ice shelf, Antarctic
Peninsula, over the periods 2002–2006 and 2006–2009 based on repeat optical
satellite data. The velocity field of the entire ice shelf is measured using
repeat low resolution MODIS data (250 m spatial resolution). The
measurements are validated for two ice shelf sections against repeat medium
resolution Landsat 7 ETM+ pan data (15 m spatial resolution). Horizontal
surface velocities are obtained through image matching in both frequency and
spatial domain, and the two methods compared. The uncertainty in the
displacement measurements turns out to be less than 70 m for the MODIS
derived data, and less than 15 m for the Landsat derived ones. The
difference between MODIS and Landsat based speeds is &amp;minus;15.4 m a&lt;sup&gt;&amp;minus;1&lt;/sup&gt;
and 13.0 m a&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, respectively, for the first period for the two
different validation sections on the ice shelf, and &amp;minus;26.7 m a&lt;sup&gt;&amp;minus;1&lt;/sup&gt; and
27.9 m a&lt;sup&gt;&amp;minus;1&lt;/sup&gt; for the second period for the same sections. This leads
us to conclude that repeat MODIS images are well suited to measure ice shelf
velocity fields and monitor their changes over time. The frequency domain
image correlation method seems better suited for this purpose because it is
faster, produces fewer mismatches, and is able to match images with regular
noise and data voids. The latter makes it possible to match Landsat 7 ETM+
images even after the 2003 failure of the Scan Line Corrector (SLC off) that
leaves significant image sections with no data. Image matching based on the
original 12-bit radiometric resolution MODIS data produced slightly better
results than using the 8-bit version of the same images. Streamline
interpolation from the obtained surface velocity field on Larsen C indicates
ice travel times of up to 450 to 550 a between the inland boundary and the
ice shelf edge. In a second step of the study we test our method successfully
on 10 other ice shelves around Antarctica demonstrating that the approach
presented could in fact be used for large scale monitoring of ice shelf
dynamics.</abstract>
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</article>

