Glacier geometry and elevation changes on Svalbard (1936-90): a baseline dataset

摘要

This study uses older topographic maps made from high-oblique aerial photographs for glacier elevation change studies. We compare the 1936/38 topographic map series of Svalbard (Norwegian Polar Institute) to a modern digital elevation model from 1990. Both systematic and random components of elevation error are examined by analyzing non-glacier elevation difference points. The 1936/38 photographic aerial survey is examined to identify areas with poor data coverage over glaciers. Elevation changes are analyzed for seven regions in Svalbard (～5000 km2), where significant thinning was found at glacier fronts, and elevation increases in the upper parts of the accumulation areas. All regions experience volume losses and negative geodetic balances, although regional variability exists relating to both climate and topography. Many surges are apparent within the elevation change maps. Estimated volume change for the regions is ?1.59±0.07 km3 a?1 (ice equivalent) for a geodetic annual balance of ?0.30 ma?1 w.e., and the glaciated area has decreased by 16% in the 54 year time interval. The 1936-90 data are compared to modern elevation change estimates in the southern regions, to show that the rate of thinning has increased dramatically since 1990.