EGU2020-18633
https://doi.org/10.5194/egusphere-egu2020-18633
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Multi-year observations of calving and front characteristics of two marine terminating outlet glaciers

Andrea Walter1,2, Martin P. Lüthi1, Martin Funk2, and Andreas Vieli1
Andrea Walter et al.
  • 1University of Zurich, Faculty of Science, Geography, Zürich, Switzerland (andrea.walter@geo.uzh.ch)
  • 2ETH Zurich, VAW, Zürich, Switzerland

We observed two outlet glaciers in West- and Nordwest-Greenland with a terrestrial radar interferometer (TRI), pressure sensors and time-lapse cameras over six and two years, respectively. The resulting detailed dataset provides us with insights on the calving process and the changes in front geometry over the last years. Since the two glaciers are characterised by different geometries and velocity fields, the influence of those parameters on the calving process can be investigated. The combination of the three different observation methods enable us to overcome their individual disadvantages. With the time-lapse camera taking pictures of the glacier front every 10 seconds, we detect all calving events of different sizes and styles but cannot quantify the volume. We used the TRI to quantify the volumes of aerial calving events by DEM differentiation. Further, calving waves measured with pressure sensors are used to distinguish between different calving types. We develop a relationship between calving volumes and wave heights and use this as an additional indirect method to estimate calving volumes. We find that the calving style and size as well as the front geometry is mainly controlled by the bed topography and the presence of a subglacial discharge plume. The location of the plume is observed to migrate from year to year, which leads also to changes in the calving pattern. Calving style and pattern as well as glacier velocity fields and geometry changes are additionally compared with environmental conditions such as the air temperature and the presence of ice-mélange in the proglacial fjord. In years with an early spring we find different front characteristics and calving patterns than for years with colder conditions.

How to cite: Walter, A., Lüthi, M. P., Funk, M., and Vieli, A.: Multi-year observations of calving and front characteristics of two marine terminating outlet glaciers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18633, https://doi.org/10.5194/egusphere-egu2020-18633, 2020

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Display material version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-18633, William D. Harcourt, 18 May 2020

    Hi Andrea,

    Thank-you for this interesting study and answering my questions during the EGU live chat session. I have an additional question:

    1. Did you encounter any multipath intereference effects caused by reflections from the water surface onto the ice cliff? Could this alter some of your calving event measurements?

    I look forward to your reply,

    Will

  • AC1: Comment on EGU2020-18633, Andrea Walter, 19 May 2020

    Hi Will

    For a large part of the front we do not expect MPI effects as we have an elevated position of the TRI and vertical or steep ice cliffs. Additionally, we look at very short timesteps and within those the reflective surface is not changing considerably. And finally to reduce the uncertainty we use several filtering methods and thus we only extract calving events of a minimum volume. Thus I do not think that MPI effects our calving event measurements.

    I hope I answered your question,

    Andrea

    • CC2: Reply to AC1, William D. Harcourt, 19 May 2020

      Thank-you for your reply and indeed this does answer my question. I look forward to seeing more of your work using the GAMMA TRI in the future!

      Will