This file contains information about the data archived for the experiments and figures presented in Leguy et al. (2021). For questions about this archive, please contact Gunter Leguy at gunterl@ucar.edu. The experiments use the open-source Community Ice Sheet Model (CISM) (https://github.com/ESCOMP/CISM), and in particular the tag “CISM_MELT_PARAM” (https://doi.org/10.5281/zenodo.4784788). This release is an update of CISM v2.1, as described by Lipscomb et al. (2019). The updated version includes new physics options and parameterizations to support grounding line and basal melt parameterization. Most of the files in this archive have been lossless compressed. References Lipscomb, W. H., Price, S. F., Hoffman, M. J., Leguy, G. R., Bennett, A. R., Bradley, S. L., Evans, K. J., Fyke, J. G., Kennedy, J. H., Perego, M., Ranken, D. M., Sacks, W. J., Salinger, A. G., Vargo, L. J., and Worley, P. H.: Description and evaluation of the Community Ice Sheet Model (CISM) v2.1, Geosci. Model Dev., 12, 387–424, https://doi.org/10.5194/gmd-12-387-2019, 2019. Leguy, G. R., Lipscomb, W. H., and Asay-Davis, X. S.: Marine ice-sheet experiments with the Community Ice Sheet Model, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2020-304. Accepted for publication in The Cryosphere, 2021. Asay-Davis, X. S., Cornford, S. L., Durand, G., Galton-Fenzi, B. K., Gladstone, R. M., Gudmundsson, G. H., Hattermann, T., Holland, D. M., Holland, D., Holland, P. R., Martin, D. F., Mathiot, P., Pattyn, F., and Seroussi, H.: Experimental design for three interrelated marine ice sheet and ocean model intercomparison projects: MISMIP v. 3 (MISMIP+), ISOMIP v. 2 (ISOMIP+) and MISOMIP v. 1 (MISOMIP1), Geosci. Model Dev., 9, 2471–2497, https://doi.org/10.5194/gmdd-9-2471-2016, 2016. Cornford, S.L., Seroussi, H., Asay-Davis, X.S., Gudmundsson, G.H., Arthern, R., Borstad, C., Christmann, J., Dias dos Santos, T., Feldmann, J., Goldberg, D. and Hoffman, M.J., 2020. Results of the third Marine Ice Sheet Model Intercomparison Project (MISMIP+). The Cryosphere, 14(7), pp.2283-2301. Pattyn, F., Perichon, L., Durand, G., Favier, L., Gagliardini, O., Hindmarsh, R. C., Zwinger, T., Albrecht, T., Cornford, S., Docquier, D., and et al.: Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison, J. Glaciol., 59, 410–422, https://doi.org/10.3189/2013JoG12J129, 2013. ################################# # Main folders in the archive # ################################# The archive contains two main folders: MISMIP3d: contains the files used to initialize and run the MISMIP3d experiments, the model output files, and the post-processed grounding line position files. MELT_experiments: contains the files used to initialize and run the spins-ups and the basal melt experiments, the corresponding model output files, and the post-processed grounding line position files. ################################ # Experiment characteristics # ################################ The experiments are run with different Stokes approximations, resolutions, basal friction laws, grounding line parameterizations, and basal melt parameterizations. As described in Leguy et al. (2021), there are two types of experiments: (1) grounding line parameterization experiments using the MISMIP3d experimental setup (Pattyn et al. 2013), and (2) sub-shelf melt parameterization experiments using the MISMIP+ experimental setup (Asay-Davis et al. 2016, Cornford et al. 2020). The grounding line parameterization experiments vary the following model options: * Stokes approximation: SSA, DIVA, Blatter-Pattyn * Grid resolution: 8km, 4km, 2km, 1km, 0.5km * Basal friction: p = 0 (power law), p = 0.5 (Schoof law), p = 1 (Schoof law) * Grounding line parameterization (GLP): no GLP, with GLP The melt parameterization experiments use only DIVA with a GLP, and vary the following options: * Grid resolution: 8km, 4km, 2km, 1km, 0.5km (the 0.5km experiments are labelled below as p5km) * Basal friction: p = 0 (power law), p = 0.5 (Schoof law), p = 1 (Schoof law) * Basal melt parameterization: Flotation condition melt parameterization (FCMP), Partial melt parameterization (PMP), No melt parameterization (NMP). See instructions at the end of this document on how to modify the configuration files to run with different options. #################################### # MISMIP3d folder organization # #################################### This folder relates to Section 3 and the introduction of Section 4 in the paper. It contains four folders: “Initial”, “SteadyState”, “Transient”, and “Melt”. Each of these folders (besides “Initial”) contains a configuration file and subfolders. The configuration files provide examples of the options used to run the model. Details on subfolders are given below. # Initial # Contains the initial profiles used to start the “Stnd” experiments for each resolution. The file naming follows this logic: “Init.Resolution.nc”, where “Resolution” is the resolution of the experiment. For example, the file “Init.2km.nc” is the initial profile for a run with a resolution of 2km. # SteadyState # Contains data related to Section 3.2 and the output for the “Stnd” and “P75R” experiments. It includes 3 subfolders: - Output: contains the model output files for each experiment. The file naming convention is: ExperimentName_StokesApproximation_BasalSlidingOption_UseOfGLP_Resolution.output.nc. For example, the file “Stnd_DIVA_p_0.5_noGLP_8km.output.nc” refers to: * ExperimentName: Stnd * StokesApproximation: DIVA * BasalSlidingOption: p_0.5 (p=0.5) * UseOfGLP: noGLP (meaning no GLP is used) * Resolution: 8km - Restart: contains the last time slice of the restart files from the “Stnd” experiments (necessary to run the P75S experiment). The file naming convention is the same as in the “Output” folder, except that “output” is replaced with “restart”. - GroundingLine: contains the post-processed grounding line positions of the experiments. The file naming convention is the same as in the “Output” folder, except that “output” is replaced with “GL” (grounding line). # Transient # Contains data related to Section 3.3 and the output for the P75S and the first 100 years of the P75R experiments (labelled as P75R_100 in the file names). It includes the same three subfolders as in the SteadyState folder, with a similar naming convention. The “Restart” folder contains the last time slice of the restart files from the P75S experiments (necessary to run the P75R or P75R_100 experiments). # Melt # Contains data related to the beginning of Section 4, describing experiments that test the impact of melt parameterizations on unbuttressed ice shelves. It includes two subfolders, “Output” and “GroundingLine”, whose file naming convention is similar to the other main folders. ############################################ # MELT_experiments folder organization # ############################################ This folder relates to Section 4. It includes two subfolders: “Spinup” and “Experiments”. # Spinup # Contains an example of a configuration file used to run the model, and 2 subfolders with the files needed to initialize the spin-ups at different resolutions, along with the last time slices of the restart files needed to initialize the transient melt experiments. The configuration file provides an example for a spin-up at a resolution at 8km. The “Common” subfolder contains the files related to moderate and high basal melt rates and the calving experiments. The “Slow_Shelf” subfolder contains the files needed to initialize and run the slow-moving ice shelf experiment. Both subfolders contain a subfolder called “Initial” and several files. The files are the last time slices of the restart files needed to begin the Ice1r or Ice2r experiments. The naming follows this logic: StokesApproximation_Experiment_BasalSlidingOption_Resolution.restart.nc. For example, the file “DIVA_Spinup_p_1.0_1km.restart.nc” refers to: * StokesApproximation: DIVA * Experiment: Spinup * BasalSlidingLaw: p=1.0 * Resolution: 1km The subfolder “Initial” contains the fields to initialize the spin-ups. The file naming follows this logic: Init.Resolution.nc, where Resolution = 8km, 4km, 2km, 1km, p5km (0.5km). # Experiments # Contains 4 folders: “Moderate_Basal_Melt”, “High_Basal_Melt”, “Calving”, and “Slow_Shelf”. * The “Moderate_Basal_Melt” folder contains data related to Section 4.2 and the output for the moderate basal melt rate experiments. * The “High_Basal_Melt” folder contains data related to Section 4.3 and the output for the high basal melt rate experiments. * The “Calving” folder contains data related to Section 4.4 and the output for the calving experiments. * The “Slow_Shelf” folder contains data related to section 4.5 and the output for the slow-moving ice shelf experiments. Each of these 4 folders has similar contents: an example of a configuration file to run an experiment with specific options related to the melt scenario, and three subfolders, “Output”, “Restart”, and “GroundingLine”. - “Output”: contains the model output fields for each experiment. The file naming follows this logic: StokesApproximation_MeltExperimentName_ExperimentName_BasalSlidingOption_MeltParameterization_Resolution.output.nc. For example, the file “DIVA_Moderate_Ice1r_p_0.5_PMP_p5km.output.nc” refers to: * StokesApproximation: DIVA * MeltExperimentName: Moderate * ExperimentName: Ice1r * BasalSlidingOption: p=0.5 (p_0.5) * MeltParameterization: PMP * Resolution: 0.5km (p5km) - “Restart”: contains the last time slice of the restart files necessary to continue the experiments. The last time slices of experiments Ice1r (Ice2r) are necessary to start experiments Ice1rr and Ice1ra (Ice2rr and Ice2ra). The last time slices of experiments Ice1rr and Ice1ra (Ice2rr and Ice2ra) are necessary to start experiments Ice1rrx and Ice1rax (Ice2rrx and Ice2rax), respectively. The file naming convention is the same as in the “Output” folder, except that “output” is replaced with “restart”. - “GroundingLine”: contains the grounding line position of all saved output for each experiment. The file naming convention is the same as in the “Output” folder, except that “output” is replaced with “GL”. ############## # Configuration # ############## This section describes how to modify the configuration script with the different options used in the paper. To vary the resolution, modify the section [grid] and the time step in the [time] section. For 8km; 4km; 2km; 1km; 0.5km respectively: [grid] ewn = 84; 164; 324; 644; 1284 nsn = 10; 20; 40; 80; 160 dew = 500.0 dns = 500.0 [time] dt = 2.0; 2.0; 1.0; 0.5; 0.25 To vary the ice softness parameter “A”, modify “default_flwa” in the [parameter] section. To vary the basal sliding law, modify “p_ocean_penetration” in the [parameter] section. This parameter is the same as “p” in the paper. To vary the Stokes approximation, modify “which_ho_approx” in the [ho_options] section: * which_ho_approx = 1 for SSA * which_ho_approx = 4 for DIVA * which_ho_approx = 2 for BP To vary the use of the GLP, modify “which_ho_ground” in the [ho_options] section: * which_ho_ground = 0 for no GLP * which_ho_ground = 2 for using a GLP To vary the application of basal melt under floating ice, modify “bmlt_float” in the [options] section: * bmlt_float = 0 implies no melt of floating ice * bmlt_float = 3 implies melt under floating ice To vary the melt parameterization under floating ice, modify “which_ho_ground_bmlt” in the [ho_options] section: * which_ho_ground_bmlt = 0 to use FCMP * which_ho_ground_bmlt = 1 to use PMP * which_ho_ground_bmlt = 2 to use NMP