Comparing Traditional Mass Balance Measurements with Long-term Volume Change Extracted from Topographical Maps: A Case Study of Storbreen Glacier in Jotunheimen, Norway, for the Period 1940–1997

Storbreen glacier is situated in the western part of Jotunheimen, a mountain area in central southern Norway. Annual mass balance data have been recorded since 1949. In addition, detailed topographical maps at the scale 1:10,000 exist from the years 1940, 1951, 1968, 1984 and 1997. In this paper, volume change calculated from maps is compared with annual mass balance data. The volume change was in reasonable agreement with the measured cumulative mass balance for the periods 1940–1951 and 1968–1984; however, for the periods 1951–1968 and 1984–1997, the mass balance measurements showed larger negative values than obtained from map comparisons. One obvious reason for this is the inaccuracy of the contour lines in the upper areas of the glacier on maps from 1940 and 1951. Other factors influencing the result are tested, and also suggestions are given for improving the techniques for mapping glacier volume changes.