Abstract:

Mass changes of the Austre Lovénbreen Arctic valley glacier have been studied using elevation changes based on high-precision RTK-GPS measurements. Using RTK-GPS data, several spatial interpolation methods were compared to produce a digital elevation model (DEM) of the glacier surface. Considering the smoothness of the glacier surface, the natural neighbor method was considered most suitable for generating the DEM. Two approaches were compared for evaluating the elevation changes of the glacier during 2013–2015: using DEMs generated from direct surface interpolation of RTK-GPS points and calculating the elevation bias of crossover points from RTK-GPS profiles of different years. The results showed that elevation changes calculated from crossover points were much more accurate than using the direct surface interpolation method, which had obvious errors in GPS empty areas. A density assumption for ice and snow was used to convert elevation change to water equivalent to study the mass balance. Assuming density of 900 and 500 kg m^-3 in the ablation and accumulation zones, respectively, the corresponding mass balance in 2013–2014 and 2014–2015 was -0.277 and 0.065 m w.e., respectively. These results differed slightly from classical glaciological mass balances primarily because of the discrepancy of the observation period and potential subglacial mass changes. The correlation between the elevation changes of crossover points and their corresponding altitude was determined. Despite some anomalies in certain regions, strong correlation was found between mass change and altitude, i.e., some mass accumulation occurred in high-altitude areas, while mass loss increased with decreasing altitude. The annual mean gradient of mass change versus altitude was approximately 2.67‰.

Key words: elevation change, Svalbard, mass balance, Arctic