Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison

TitleDesign and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison
Publication TypeJournal Article
Year of Publication2018
AuthorsGoelzer, Heiko, Nowicki Sophie, Edwards Tamsin, Beckley Matthew, Abe-Ouchi Ayako, Aschwanden Andy, Calov Reinhard, Gagliardini Olivier, Gillet-Chaulet Fabien, Golledge Nicholas R., Gregory Jonathan, Greve Ralf, Humbert Angelika, Huybrechts Philippe, Kennedy Joseph H., Larour Eric, Lipscomb William H., Le clec’h Sebastien, Lee Victoria, Morlighem Mathieu, Pattyn Frank, Payne Antony J., Rodehacke Christian, Rückamp Martin, Saito Fuyuki, Schlegel Nicole, Seroussi Helene, Shepherd Andrew, Sun Sainan, van de Wal Roderik, and Ziemen Florian A.
JournalThe Cryosphere
Volume12
Number4
Pages1433-1460
Date Published04/2018
Abstract

Earlier large-scale Greenland ice sheet sea-level projections (e.g. those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of this initMIP-Greenland intercomparison exercise is to compare, evaluate, and improve the initialization techniques used in the ice sheet modeling community and to estimate the associated uncertainties in modeled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project Phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of (1) the initial present-day state of the ice sheet and (2) the response in two idealized forward experiments. The forward experiments serve to evaluate the initialization in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly); they should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions, and initialization techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.

URLhttp://dx.doi.org/10.5194/tc-12-1433-2018
DOI10.5194/tc-12-1433-2018
Journal: The Cryosphere
Year of Publication: 2018
Volume: 12
Number: 4
Pages: 1433-1460
Date Published: 04/2018

Earlier large-scale Greenland ice sheet sea-level projections (e.g. those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of this initMIP-Greenland intercomparison exercise is to compare, evaluate, and improve the initialization techniques used in the ice sheet modeling community and to estimate the associated uncertainties in modeled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project Phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of (1) the initial present-day state of the ice sheet and (2) the response in two idealized forward experiments. The forward experiments serve to evaluate the initialization in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly); they should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions, and initialization techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.

DOI: 10.5194/tc-12-1433-2018
Citation:
Goelzer, H, S Nowicki, T Edwards, M Beckley, A Abe-Ouchi, A Aschwanden, R Calov, O Gagliardini, F Gillet-Chaulet, N Golledge, J Gregory, R Greve, A Humbert, P Huybrechts, J Kennedy, E Larour, W Lipscomb, S Le clec’h, V Lee, M Morlighem, F Pattyn, A Payne, C Rodehacke, M Rückamp, F Saito, N Schlegel, H Seroussi, A Shepherd, S Sun, R van de Wal, and F Ziemen.  2018.  "Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison."  The Cryosphere 12(4): 1433-1460, pp. 1433-1460.  https://doi.org/10.5194/tc-12-1433-2018.