EGU22-8882
https://doi.org/10.5194/egusphere-egu22-8882
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Implementation of the Zoet-Iverson basal sliding law in CISM

Tim van den Akker1, William H. Lipscomb2, Gunter R. Leguy2, Willem Jan van de Berg1, and Roderik S.W. van de Wal1,3
Tim van den Akker et al.
  • 1Utrecht University, Institute for Marine and Atmospheric research Utrecht (IMAU), Netherlands (t.vandenakker@uu.nl)
  • 2Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, United States
  • 3Departement of Physical Geography, Utrecht University, Netherlands

There are large uncertainties in model predictions of the Antarctic Ice Sheet (AIS) contribution to future sea level rise. One source of model uncertainty is the description of basal friction. Here, we implement a new basal sliding law, developed by Zoet and Iverson (2020), in an updated version of the Community Ice Sheet Model (CISM). The Zoet-Iverson sliding law combines properties of two previously used sliding laws: power-law behavior in areas with slow-moving ice and coulomb-law behavior in fast-moving ice streams and outlet glaciers. We adress the behavior and performance of the Zoet-Iverson law in CISM using AIS spin-up procedures developed for the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We invert a non-dimensional coefficient in the Zoet-Iverson law to match modelled and observed thickness for grounded ice. Ocean temperatures are tuned to nudge ice-shelf thickness via the basal melt rates. These tuning processes are Antarctic-wide, but we focus on the Amundsen Sea region. We then advance the model forward to better represent the present-day Thwaites glacier, by inverting for observed ice velocity and by changing the ocean forcing. The main results from this run are the sub-shelf ocean temperature perturbation, thickness, and velocity profile of Thwaites glacier. Results are compared with different sliding laws to demonstrate the effect of the Zoet-Iverson law on the representation of the ongoing retreat. 


Zoet, L.K. & Iverson, N.R. (2020). A slip law for glaciers on deformable beds. In: Science 368 (6486), pages 76-78. DOI: 10.1126/science.aaz1183

How to cite: van den Akker, T., Lipscomb, W. H., Leguy, G. R., van de Berg, W. J., and van de Wal, R. S. W.: Implementation of the Zoet-Iverson basal sliding law in CISM, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8882, https://doi.org/10.5194/egusphere-egu22-8882, 2022.