En massebalansestudie av to arkeologiske isfonner i Oppdalsområdet

Abstract

The focus of this thesis is on the mass balance of two ice patches, Kringsollfonna and Evighetsfonna, in the area of Oppdal where archeological finds have been made. Archeological artifacts preserved within the ice patches and dating back as far as 3500 years BP have led to an interest among glaciologists, as these discoveries indicate that the ice patches have existed for a similar amount of time. The fact that the ice patches are found in periglacial areas, well below regional ELA, raises questions about processes related to their stable mass balance over time. In this study, the mass balance is measured through field studies, probing, snow density measurements and differential-GPS measurements over one mass balance season. The winter and summer balance is also modeled by the HBV-model, which is used as a basis of comparison for mass balance measurements and to analyze differences between mass balance seasons. The year 2012 was a positive mass balance season due to high levels of snowfall and the redistribution of snow. By analyzing the modeled and measured winter balance, the importance of the wind effect on snow accumulation is found, and shows a higher local accumulation on the ice patches than the estimated regional snowfall itself. In this sense, local terrain parameters and wind are crucial for accumulation on the ice patches, and the accumulation occurring over winter seems to be the most important factor for positive and stable mass balance. The ice patches differ in accumulation and the ablation patterns; the Kringsollfonna patch has qualities which are more closely related to the definition of an ice patch, whereas the Evighetsfonna patch is more characteristic of a small glacier.