April 2014 Marine ice-sheet model inter-comparison splinter group meeting (MISMIP) at EGU

At the EGU Assembly in April 2014, a Marine Ice Sheet Model Intercomparison Projects (MISMIP) splinter meeting was organized to gauge the interest in the need for a follow-up of MISMIP3d. What questions are still unanswered? Are ice sheet models ready to be coupled to ocean models, or is there a need for an intermediate evaluation (benchmark)? The results of the discussion are given below.

At the splinter meeting, the current context of marine ice sheet intercomparisons was presented by F. Pattyn, recalling the main results of the MISMIP (Pattyn et al. 2012) and MISMIP3d (Pattyn et al. 2013, Pattyn and Durand 2013) exercises, and pointing towards the CliC-West Antarctica Glacier-Ocean Modelling (WAGOM) initiative. The latter has the objective of coordinating international efforts that aim at building an ensemble of outlet glacier - ocean modeling systems and improve projections of West-Antarctic contribution to sea-level rise. A large consensus in the audience was that improvements in the development of ice-sheet modeling in general and of a better representation of outlet glacier dynamics in particular should continue simultaneously to the CLiC-WAGOM initiative. A new intercomparison exercise of marine ice sheet models should therefore be envisaged. The main question to be addressed by this exercise should probably be the ability of ice flow models to not diverge to much in their projection of SLR contribution on a century time scale. Therefore, in comparison with previous MISMIPs a more particular focus on interactions between outlet glacier dynamics and sub ice shelf melt rate should be envisaged.

During the discussions, they were some agreements between the attendants on the following points:

  1. A synthetic geometry should be preferred, probably inspired from Pine Island Glacier. The geometry proposed in Gudmundsson et al. 2012, probably with a smaller longitudinal extension could be a solution.
  2. Perturbations should be introduced through submarine melting. Oceanographers should be involved to ensure that the chosen parametrization is meaningful.
  3. Two sets of experiments should be envisaged: (i) running the steady state before running the melting perturbations, (ii) invert the basal drag to initialize the models to a given geometry, then run the melting experiments.
  4. Participants should probably provide results using different resolution to ensure convergence of their results.

A second planning meeting is proposed to be held at the IGS Conference in Chamonix (25-30 May 2014).

For more information http://homepages.ulb.ac.be/~fpattyn/mismip+/ or contact the meeting organizers:

Frank Pattyn, Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium (email: )
Gael Durand, LGGE, Grenoble, France (email: )