Glacier front variatons in Sweden: 2015-2022

Sammanfattning: This study aims at increasing the amount of data available on recent past Swedish glacier front variations, at improving the knowledge on the present behavior of these glaciers, and at contributing to the defnition of the guideline for future of glacier front observations in Sweden. To do so, the study proposes Sentinel-2 based yearly front variation measurements for 22 Swedish glaciers between 2015 and 2022, calculated based on the multicentreline approach of the MaQiT tool. It also assesses the uncertainty of Sentinel-2 based mapping by comparing it to 0.48 m spatial resolution aerial imagery based mapping and to field based mapping conducted on four northern Sweden glaciers during the end of the summer 2022: Kaskasatj SE, Kebnepakteglaciären, Mårmaglaciären, and Storglaciären. The fieldwork included handheld GNSS, UAV photogrammetry, and total station survey in order to compare the three methods in the mapping of glacier fronts. This study also compares the measured glaciers front variations to climatic factors and glaciers boundary conditions. The resulting glacier front variations in Sweden between 2015 and 2022, averaged over all glaciers studied, is −10.28 m yr−1. Small glaciers retreated on average 0.51 % of their length per year, while large glaciers retreated on average 0.35 % per year. This study highlights the importance of recording yearly front positions of a large amount of glaciers, and therefore encourages for the future the use of satellite imagery to observe all Swedish glaciers fronts on a yearly basis. It also supports the conduction of regular UAV photogrammetry surveys to provide high resolution mapping of a sample of glacier fronts chosen for their vicinity with the Tarfala Research Station, the Swedish field centre for glaciological and alpine research.