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| Titel |
Mass balance of Langjökull ice cap in Iceland during different climate settings; deduced from multi-temporal DEM´ s from 1936 to 2008, and in situ mass balance measurements 1997-2009 |
| VerfasserIn |
Finnur Palsson, Sverrir Guðmundsson, Helgi Bjornsson, Etienne Berthier, Hannes Haraldsson |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042752
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| Zusammenfassung |
| We describe the mass balance of Langjökull ice cap (Â 920 km2, Â 190 km3) during several
time intervals that span most of the 20th century until present, hence for different climate
conditions. Langjökull located in midwest Iceland is highly sensitive to climate change, with
an elevation range 460 - 1440 m a.s.l., zero balance ELA of  960 m and a zero balance mass
turnover of 1.75 m/yr w. eq..
Since 1997 the mass balance of Langjökull has been monitored by conventional mass
balance measurements at 22 sites on the glacier, and from this data digital maps of the winter,
summer and annual balance have been produced for every glaciological year. The mass
balance was also assessed from estimation of ice volume changes by comparing
several DEM’s: from 1936 and 1945-46 (from digitized contour lines of revised
published maps based on aerial photographs and geodetic survey), 1986 (from digitized
contour lines of maps based on aerial photographs and point measurements from an
inertial navigation system), 1997 (from D-GPS surface profile survey, about 1 km
between lines) and 2004 (SPOT5-HRG). The accuracy of the SPOT5-HRG DEM was
estimated to be within 2 m in elevation by analyzing the residue of the DEM and an
ensemble of points and profile elevation data surveyed by kinematic GPS, both on and
in near vicinity of the ice cap. The SPOT5-HRG DEM was used as a reference
map for both co-registration and to improve the accuracy and details of the older
maps.
The difference between the 1997-2004 net balance estimated by volume change and in
situ measurements is negligible (~10 cm w. eq. ). During the two extremely warm periods
1936-1946 and 1997-2008 the mass balance was similar; -1.6 and -1.4 m/yr w. eq.,
respectively. The colder climate 1946-1986 and cooler yet in 1986-1997 resulted in mass
balance close to zero; -0.3 and -0.2 m/yr w. eq., respectively. |
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