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  • Cambridge University Press (CUP)  (2)
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  • Cambridge University Press (CUP)  (2)
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  • 1
    In: Annals of Glaciology, Cambridge University Press (CUP)
    Abstract: We use the apparent horizontal shift of an englacial tephra layer outcrop to calculate local glacier mass balance on Sléttjökull, a lobe of Mýrdalsjökull in Southern Iceland. For this approach, the dipping angle of the englacial tephra layer in the glacier upstream of the outcrop and the flow velocity of the ice need to be known. An earlier investigation was expanded by the application of ground-penetrating radar, detecting the depth of the tephra along tracks with a total length of 10 km. Interpolation between the tracks enables us to derive the dipping angle of the layer along several flow lines. Together with glacier surface velocities, determined from feature tracking, we are able to estimate the local surface mass balance from the horizontal displacement of the tephra outcrop using freely available satellite imagery without additional fieldwork. The earlier local balance series was extended to the period 2014/15 to 2019/20. Although the results for the individual profiles differ slightly from each other, they show the same temporal pattern and clear variations from year to year. The results are compared to traditional mass-balance data from Hofsjökull. The two series show a good agreement in their interannual variability.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2023
    In:  Journal of Glaciology
    In: Journal of Glaciology, Cambridge University Press (CUP)
    Abstract: Crevasses pose severe risks for mountaineers and field glaciologists. Smaller cracks between 0.5 and 2 m are still dangerous, but often not visible in medium resolution satellite imagery. If they are snow covered, they are completely undetectable by optical sensors. We set out to develop an approach to detect potentially crevassed areas by a minimum of geometric data, and to make the method generally applicable to glacier regions. On Vernagtferner, we compared a reference dataset of crevasses observed in high-resolution optical imagery with the curvature of the ice surface and the spatial gradients in driving stress. Both parameters can be derived from a digital surface model and a bedrock model, derived from ice thickness measurements. The correlation patterns show that crevasses preferably form in convex areas and in areas where the driving stress rapidly increases. This corresponds with the theory of crevasse formation. Although the method still misclassifies larger parts, the approach has the potential to define probable non-crevassed areas as well as to aid the planning of safe routes.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2140541-4
    SSG: 14
    Location Call Number Limitation Availability
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