Climate - glacier links on Bogerbreen, Svalbard : Glacier mass balance investigations in central Spitsbergen 2004 / 2005

Abstract\nGlaciers are key indicators for climate change. Mass balance studies form the important link between advances and retreats of glaciers to changes in climate. Mass balance studies were performed in the balance year 2004/05 on Bogerbreen as part of my Master thesis. Bogerbreen is a valley glacier with a size of 3.3 km² located in central Spitsbergen, Svalbard at 78 degrees north and 15 degrees east. The direct glaciological method was applied to measure winter mass balance using snow soundings and snow pit studies. Summer balance was obtained from stake readings. The use of artificial reference horizons and shallow ice cores helped to estimate superimposed ice formation. In addition to the primary mass balance components, air temperatures were recorded on site as well as daily glacier photographs were collected, stake and glacier surface surveys performed. Ice surface velocities were measured and I generated a high resolution digital terrain model and an orthophoto of the study site. Winter balance 2004/05 was calculated to be 0.55 ± 0.08 m water equivalent. Redistribution of snow is a major control on the spatial distribution of the winter mass balance. In a more regional scale it is likely that wind drifted snow is deposited on Bogerbreen and adds significantly to the winter mass balance beside winter precipitation. Summer mass balance were calculated to - 1.35 ± 0.24 m water equivalent. Ablation decreases with increase in elevation most likely due to the influence of turbulent heat fluxes. At the middle part of the glacier, albedo effects and shading lead to a distinctive lateral summer balance asymmetry. It is likely that the spatial distribution of winter snow plays a major role causing this lateral asymmetry. The resulting net mass balance was negative in the balance year 2004/05, with - 0.80 ± 0.20 m water equivalent. Mean geodetic net balances for the period 1990 to 2003 and previous direct measured balances indicate that Bogerbreen has not been in balance with the climate for the last decades. This is in accordance with findings elsewhere on Spitsbergen.