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  • 2015-2019  (2)
  • 2018  (2)
  • 1
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    PANGAEA
    In:  Supplement to: Rückamp, Martin; Neckel, Niklas; Berger, Sophie; Humbert, Angelika; Helm, Veit (2019): Calving Induced Speedup of Petermann Glacier. Journal of Geophysical Research-Earth Surface, https://doi.org/10.1029/2018JF004775
    Publication Date: 2023-03-16
    Description: This study assesses the response on ice dynamics of Petermann Glacier, a major outlet glacier in northern Greenland, to the 2012 and a possible future calving event. So far Petermann Glacier has been believed to be dynamically stable as another large calving event in 2010 had no significant impact on flow velocity or grounding line retreat. By analyzing a time series of remotely sensed surface velocities, we find an average acceleration of 10% between winter 2011/2012 and winter 2016/2017. This increase in surface velocity is not linear but can be separated into two parts, starting in 2012 and 2016 respectively. By conducting modelling experiments, we show that the first speed-up can be directly connected to the 2012 calving event, while the second speed-up is not captured. However, on recent remote sensing imagery newly developing fractures are clearly visible ~12,km upstream from the terminus, propagating from the eastern fjord wall to the center of the ice tongue, indicating a possible future calving event. By including these fracture zones as a new terminus position in the modelling domain we are able to reproduce the second speed-up, suggesting that surface velocities remain on the 2016/2017 level after the anticipated calving event. This indicates that, from a dynamical point of view, the terminus region has already detached from the main ice tongue.
    Keywords: AWI_Glac; File format; File name; File size; Glaciology @ AWI; North Greenland; Petermann_Glacier; RADAR; Radar profile; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 72 data points
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2019-08-21
    Description: Ice shelves control the dynamic mass loss of ice sheets through buttressing and their integrity depends on the spatial variability of their basal mass balance (BMB), i.e. the difference between refreezing and melting. Here, we present an improved technique – based on satellite observations – to capture the small-scale variability in the BMB of ice shelves. We use mass conservation in a Lagrangian framework based on high-resolution surface velocities, atmospheric-model surface mass balance and hydrostatic ice-thickness fields (derived from TanDEM-X surface elevation). Spatial derivatives are implemented using the total-variation differentiation, which preserves abrupt changes inflow velocities and their spatial gradients. Such changes may reflect a dynamic response to localized basal melting and should be included in the mass budget. After testing our technique on the Roi Baudouin Ice Shelf, East Antarctica, we test our methodology on other ice shelves, with different flow regimes. Whereas the detected large-scale pattern in the BMB is very similar to previous and coarser studies, we are nevertheless able detect small-scale features in the BMB with unprecedented detail (10 m gridding). Examples include elevated melting at an ice-shelf channel’s flank and surface lowering of an elliptical surface depression. Although the absolute, satellite-based BMB values remain uncertain, we have high confidence in the spatial variability on sub-kilometre scales. This work highlights expected challenges for a full coupling between ice and ocean models.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Format: application/pdf
    Location Call Number Limitation Availability
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