Effects of snow-free season, temperature and radiation variations on the retreat of Linné glacier, Svalbard

Sammanfattning: Linné glacier has retreated approximately 1.8 km since 1936 and 1 km between 1995 and 2019. Linné glacier is following the same trend as other glaciers around Svalbard. Linné glacier is a well-monitored glacier with a time series of air temperature, incoming solar radiation and snow height data since 2003. Annual recordings of the glacier margin from 2007, allows for an accurate reconstruction of the glacier's retreat. The aim of this thesis is to evaluate how climatic factors such as the length of the snow free season, air temperature and incoming solar radiation affect the yearly retreat of Linné glacier over the course of 13 years. This will be done by mapping the annual retreat of the glacier and calculating the length, average air temperature and average incoming solar radiation of each snow free season. In 2019 the glacier margin was recorded by a handheld GPS and a drone to make a comparison between both methods. Linné glacier is negatively affected by an increase in air temperature, increase in incoming solar radiation and longer snow free season. In total the glacier area retreat amounted to about 30.57 ha over the course of 13 years, from 2007 until 2019. An increase of 1 °C in air temperature will result with a glacier retreat of 0.44 ha. Incoming solar radiation has the highest impact on Linné glacier retreat compared to the other climatic factors. When calculating the sum of the daily average air temperature of each snow free season, a stronger correlation was observed with the area of retreat. An increase in the snow free season length is observed, caused by earlier melt onset and later freeze up. Lastly, photogrammetry is a more suitable way of data collecting the glacier margin coordinates than using a handheld GPS. These findings are relevant for glacier retreat studies and contribute towards an improved understanding of glacier behavior in Svalbard.