Effects from Firn Density on Radar Derived Depth to Perennial Firn Aquifer, Lomonosovfonna, Svalbard

Detta är en Kandidat-uppsats från Uppsala universitet/Luft-, vatten- och landskapslära

Sammanfattning: As the climate is changing, there are clear impacts on the mass balance of glaciers. A glacier can be defined as the result of sufficient accumulation, in the form of snow and rain, compared to its ablation, the different types of glacial loss, a balance that then determines the size of the glacier. A phenomenon in glacial environments where processes and effects on the environment are still relatively unknown arethe so-called firn aquifers. Firn aquifers are a type of “glacial groundwater” where water seeps through the firn, a form of more compact snow, and then accumulates and forms masses of water on top of the more compact ice. These water reservoirs can then affect glacial hydrology, mass balance, and the ice dynamics in the area by acting as a buffer for the meltwater on the way to the sea, causing and intensifying hydrofracturing, lowering the glacier’s albedo as well as acting as a heat source which in turn can deform the underlying ice. In 2018 and 2019, Ground Penetrating Radar measurements were made on Lomonosovfonna, a glacier on Svalbard, to measure the position and water level of one of the glaciers’ firn aquifers. The purpose of this study is to compare the radar data with measured data of the snow and firn density (stake measured during 2012, 2014, and 2016 at three different locations) to see what effects the density profile has on the radar-derived depth measurements. For this, ArcGIS was used to plot the intersection points of 2018 and 2019, to compare the two year’s different depth to the underlying water table. Then, MATLAB was used with the stake measured density profile and interpolated with the calculated depth values with the same two-way travel time as the GPR data to correlate the depths to the same intersection points. The general result showed that the firn densityprofile did have an impact on the data, but not significantly enough to alter the overall values as the change between the two years are of the similar magnitude. There are many different variables that could have played a role in the achieved results and further research needs to be done in order to establish a more in-depth conclusion

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