21 Sep 2020

21 Sep 2020

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

The transferability of adjoint inversion products between different ice flow models

Jowan M. Barnes1, Thiago Dias dos Santos2,3, Daniel Goldberg4, G. Hilmar Gudmundsson1, Mathieu Morlighem2, and Jan De Rydt1 Jowan M. Barnes et al.
  • 1Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UK
  • 2Department of Earth System Science, University of California, Irvine, CA, USA
  • 3Centro Polar e Climático, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
  • 4School of GeoSciences, University of Edinburgh, Edinburgh, UK

Abstract. Among the most important challenges faced by ice flow models is how to represent basal and rheological conditions, which are challenging to obtain from direct observations. A common practice is to use numerical inversions to calculate estimates for the unknown properties, but there are many possible methods and not one standardised approach. As such, every ice flow model has a unique initialisation procedure. Here we compare the outputs of inversions from three different ice flow models, each employing a variant of adjoint-based optimisation to calculate basal sliding coefficients and flow rate factors using the same observed surface velocities and ice thickness distribution. The region we focus on is the Amundsen Sea Embayment in West Antarctica, the subject of much investigation due to rapid changes in the area over recent decades. We find that our inversions produce similar distributions of basal sliding across all models, despite using different techniques, implying that the methods used are highly robust and represent the physics without much influence by individual model behaviours. Transferring the products of inversions between models results in time-dependent simulations displaying variability on the order of or lower than existing model intercomparisons and process studies. While the successful transfer of inversion outputs from one model to another requires some extra effort and technical knowledge of the particular models involved, it is certainly possible and could indeed be useful for future intercomparison projects.

Jowan M. Barnes et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Jowan M. Barnes et al.

Model code and software

Úa source code G. H. Gudmundsson

Jowan M. Barnes et al.


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Short summary
Some properties of ice flow models must be initialised using observed data before they can be used to produce reliable predictions of the future. Different models have different ways of doing this. We compare the methods used by three different models, and show that they produce similar results. This demonstrates that the methods work well, and that the results from one model could potentially be used in other models without introducing large uncertainties.