Landsat-derived glacier inventory for Jotunheimen, Norway, and deduced glacier changes since the 1930s L. M. Andreassen1,2, F. Paul3, A. Kääb2, and J. E. Hausberg1,2 1Norwegian Water Resources and Energy Directorate (NVE), Oslo, Norway 2Department of Geosciences, University of Oslo, Oslo, Norway 3Department of Geography, University of Zurich, Zurich, Switzerland
Abstract. A Landsat Thematic Mapper (TM) scene from 2003 covering the Jotunheimen and
Breheimen region has been used to map the recent glacier extents using
thresholded ratio images (TM3/TM5). Orthoprojected aerial photographs and
glacier outlines from digital maps have been used to validate the method and
control the results. We further calculated glacier changes by comparing the
Landsat-derived 2003 glacier outlines with previous maps and inventories
from the 1930s, 1960s and 1980s. Our results confirm that the applied
automatic mapping method is robust and agrees with the reference
data used. Some manual editing was necessary to correct the outline at
ice-lake contacts and at debris covered glaciers. However, for most of the
glaciers no corrections were required. The most laborious task has been to
assign ID numbers and couple the new Landsat inventory to previous
inventories to assess area changes. The glaciers investigated shrank since
the 1930s with an overall area reduction of about 23% for 38 glaciers.
Since the 1960s the area reduction was 12% for 164 glaciers. Although the
general trend is glacier recession, some glaciers have
increased their size or remained nearly unchanged over these decades.
Citation: Andreassen, L. M., Paul, F., Kääb, A., and Hausberg, J. E.: Landsat-derived glacier inventory for Jotunheimen, Norway, and deduced glacier changes since the 1930s, The Cryosphere, 2, 131-145, doi:10.5194/tc-2-131-2008, 2008.