Authors: Wangensteen, Bjørn¹; Tønsberg, Ole Magnus¹; Kääb, Andreas²; Eiken, Trond¹; Hagen, Jon Ove¹

Source: Geografiska Annaler: Series A, Physical Geography, Volume 88, Number 1, March 2006 , pp. 55-74(20)

Publisher: Wiley-Blackwell

Abstract:

Velocity fields for the three outlet glaciers Nigardsbreen, Bergsetbreen and Baklibreen of Jostedalsbreen, southern Norway, have been obtained from successive orthophotos by digital image processing. The orthophotos were generated with standard digital photogrammetry. They are based on air photos acquired ten days apart in August 2001 and produced with a ground resolution of 0.5 m. Glacier displacements were calculated by matching homologous points in each orthophoto using a regular grid with 10 ??10 m resolution. Displacements, calculated using cross-correlation matching of orthophotos for Nigardsbreen, show daily movement of up to 1.34 m and agree well with GPS-measured velocities during the same period. The average velocities for the three glaciers ranged from 0.38 to 0.56 m per day. Surface elevation change have been calculated by differencing the 5 m resolution digital elevation model (DEM) obtained from the August 2001 air photos with two 25 m resolution DEMs from 1984 (Nigardsbreen) and 1993 (all three outlets). These calculations show an average increase in surface elevation of 22.1 m for Nigardsbreen between 1984 and 2001. Bergsetbreen and Baklibreen show increases of 3.2 m and 14.3 m between 1993 and 2001. In addition a DEM produced from air photos from 1997 was used for Nigardsbreen, making it possible to show how the surface elevation has changed between the years 1984, 1993, 1997 and 2001. The advance of the glacier snouts is also clearly visualized by the DEM differencing

Keywords: digital photogrammetry; glacier velocities; orthophotos; volume change

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.0435-3676.2006.00283.x

Affiliations: 1: Department of Geosciences, University of Oslo, Norway 2: Department of Geography, University of Zürich-Irchel, Zürich, Switzerland

Publication date: 2006-03-01

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