Terrestrial Laser Scanning as a Tool to Evaluate the Quality of Interpolated Ablation Stakes Data and the Uncertainty of an Arctic Glacier Mass Balance

Abstract:

A network of ablation stakes has been maintained on the Austre Lovén glacier (Svalbard) over the last 8 years. Data collected thanks to this in-situ equipment served as a basis to obtain annual mass balance values. Interpolation methods were used to generalize the values measured at the stakes to the entire surface of the glacier (4.5km²). This allows for a precise quantification of the glacier’s dynamics including areas where data are not easy to collect directly on the field such as the glacier snout or steep accumulation zones.

Over the last 4 years, repeat terrestrial laser scanning (TLS) surveys have been undertaken twice a year. Scans were acquired at the end of the expected annual snow maximum (April) and near the end of the melting season (August). Even though these scans do not cover the entire glacier, they yield high density point clouds of the glacier surface in crucial areas. The glacier terminus, the equilibrium line area and accumulation cirques were among the zones specifically scanned.

The comparison of mass balance results derived from ablation stakes data and digital elevation models (DEMs) derived from TLS measurements allowed for an assessment of the quality and uncertainty of these methods. Local variability proves higher than initially expected, especially in key areas of the glacier having the greatest impact on the global balance. Even though the Austre Lovén glacier displays a seemingly smooth and homogeneous surface, local variations have to be taken into consideration. The potential consequences of this variability on the annual mass balance will be explored.