EGU2020-21999
https://doi.org/10.5194/egusphere-egu2020-21999
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Modelling Jakobshavn Isbrae from 2009 to 2018

Matt Trevers1, Tony Payne1, Steph Cornford2, and Anna Hogg
Matt Trevers et al.
  • 1Centre for Polar Observation and Modelling, School of Geographical Sciences, University of Bristol, Bristol, UK (matt.trevers@bristol.ac.uk)
  • 2Department of Geography, Swansea University, Swansea, UK

Jakobshavn Isbrae has dramatically accelerated, thinned and retreated since the late 1990s in several stages of retreat and stagnation. Studies have indicated that the loss of buttressing due to retreat of the calving front following the disintegration of its floating ice tongue was the trigger of acceleration and thinning of the terminus, however uncertainty remains over the mechanisms controlling the timing and magnitude of the retreat.

The maximum retreat of the calving front was reached between 2013 and 2015 following the peaking of ice flow speeds in excess of 18 km yr-1. Since 2016, ice flow speeds have decelerated from this peak and the terminus has experienced a modest readvance and thickening. We calculated a calving rate for the period 2009 to 2018 which shows that terminus flow speeds and calving are closely related. Until 2009 a transient loosely bonded ice tongue formed but this feature appears not to have formed from 2010 onwards.

We aim to demonstrate that the signal of thinning and retreat can be reproduced by driving the glacier with the calculated calving rate. We used the BISICLES ice sheet model to simulate the evolution of Jakobshavn Isbrae over the past decade, with the calving front driven by the calculated 2009 – 2018 calving rate. The results of these simulations show that the response of the glacier to the applied calving rate is in line with its observed evolution over this period. We also present the results of further experiments designed to examine the mechanisms and controls on the calving retreat.

How to cite: Trevers, M., Payne, T., Cornford, S., and Hogg, A.: Modelling Jakobshavn Isbrae from 2009 to 2018, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21999, https://doi.org/10.5194/egusphere-egu2020-21999, 2020

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Display material version 3 – uploaded on 07 May 2020
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  • AC1: Welcome, Matt Trevers, 08 May 2020

    Hi EGU2020!

    I'm presenting here work which comprises a large part of my PhD (still writing!)

    Jakobshavn Isbrae is a major calving outlet glacier of the Greenland Ice Sheet. In the period between 2009 and 2018 it retreated rapidly, reaching speeds in excess of 17 km/yr before stagnating slightly and readvancing from 2015 onwards.

    Here I present the first calculated calving rate for Jakobshavn Isbrae, which shows a correlation with the terminus velocity, suggesting a possible feedback between calving rate and the evolution of the flow dynamics.

    I use the BISICLES ice sheet model to simulate the evolution of the glacier over the same period, using the calculated calving rate as a forcing on the glacier. A time-series model inversion assimilating data throughout the period improves the model's ability to capture basal conditions.

    Applying a mean annual calving rate goes some way towards capturing the general retreat and advance of the glacier throughout the period, while superimposing a seasonal signal to the calving rate reproduces the strong seasonal advance/retreat and velocity fluctuations exhibited by the glacier.

    A short video demonstration of the model can be viewed at:

    Hi EGU2020!

    I'm presenting here work which comprises a large part of my PhD (still writing!)

    Jakobshavn Isbrae is a major calving outlet glacier of the Greenland Ice Sheet. In the period between 2009 and 2018 it retreated rapidly, reaching speeds in excess of 17 km/yr before stagnating slightly and readvancing from 2015 onwards.

    Here I present the first calculated calving rate for Jakobshavn Isbrae, which shows a correlation with the terminus velocity, suggesting a possible feedback between calving rate and the evolution of the flow dynamics.

    I use the BISICLES ice sheet model to simulate the evolution of the glacier over the same period, using the calculated calving rate as a forcing on the glacier. A time-series model inversion assimilating data throughout the period improves the model's ability to capture basal conditions.

    Applying a mean annual calving rate goes some way towards capturing the general retreat and advance of the glacier throughout the period, while superimposing a seasonal signal to the calving rate reproduces the strong seasonal advance/retreat and velocity fluctuations exhibited by the glacier.

    A short video demonstration of the model can be viewed at: https://www.youtube.com/watch?v=jdLJeFsMmBY&feature=youtu.be

    Thanks, and see you next year!

    Matt (the author)

    Thanks, and see you next year!

    Matt (the author)

    • AC2: Reply to AC1, Matt Trevers, 08 May 2020

      It seems we can't edit or remove comments!

      Anyway, the video demonstration can be viewed here: https://www.youtube.com/watch?v=jdLJeFsMmBY&feature=youtu.be

Display material version 2 – uploaded on 06 May 2020, no comments
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