Mass Balance of Storglaciären During the 20th Century

The mass balance of Storglaciären is well correlated with the summer temperature at Tarfala and at other climatic stations in northern Sweden. By using regression models, Storglaciärens net balance has been estimated back to 1878. Based on this estimate the cumulative net increase in mass from 1878 to 1910 is estimated to have been 2 · 1010 kg. Since 1910 the mass loss has been 1.1 · 1011 kg, or 26% of its mass in 1910.The volume change of Storglaciären has also been calculated, from comparison of maps dating from 1949,1959,1969 and 1980, all of which are based upon aerial photographs. This change is compared with the mass balance measured in the field to determine whether there are systematic errors in the field method and if so whether they are large enough to influence the annual mass balance significantly.The volume change based on the map study is in good agreement with field measurements. This means that the systematic errors in field surveys are not larger than those in the maps, which are estimated to be about ± 10% of the cumulative mass change over the 31-year period.