4. Test simulations

These are a number of computationally rather inexpensive test simulations, of which the run-specs header files are contained in the SICOPOLIS repository.

Run repo_vialov3d25

3D version of the 2D Vialov profile (Vialov [59]),

SIA, resolution 25 km, \(t=0\ldots{}100\,\mathrm{ka}\).

Similar to the EISMINT Phase 1 fixed-margin experiment (Huybrechts et al. [41]), but without thermodynamics. Instead, isothermal conditions with \(T=-10^{\circ}\mathrm{C}\) everywhere are assumed.

Run repo_emtp2sge25_expA

EISMINT Phase 2 Simplified Geometry Experiment A,

SIA, resolution 25 km, \(t=0\ldots{}200\,\mathrm{ka}\) (Payne et al. [51]).

The thermodynamics solver for this run is the one-layer melting-CTS enthalpy scheme (ENTM), while all other runs employ the polythermal two-layer scheme (POLY) (Greve and Blatter [31]).

Run repo_grl16_bm5_ss25ka

Greenland ice sheet, SIA, resolution 16 km,

short steady-state run (\(t=0\ldots{}25\,\mathrm{ka}\)) for modern climate conditions (Fig. 4.1; unpublished).

Runs repo_grl16_bm5_{init100a, ss25ka_nudged}

Greenland ice sheet, SIA, resolution 16 km;

\(t=-100\,\mathrm{a}\ldots{}0\) for the init run without basal sliding (…_init100a),

\(t=0\,\ldots{}25\,\mathrm{ka}\) for the main run (…_ss25ka_nudged),

steady-state run for modern climate conditions, free evolution during the first 10 ka, after that gradual nudging towards the slightly smoothed present-day topography computed by the init run (Fig. 4.1; unpublished).

Fig. 4.1 Ice volume for the two steady-state simulations for Greenland, repo_grl16_bm5_ss25ka (unconstrained evolution) and repo_grl16_bm5_ss25ka_nudged (topography nudging with time-dependent relaxation time after t = 10 ka).

Run repo_ant64_bm3_ss25ka

Antarctic ice sheet, hybrid shallow-ice–shelfy-stream dynamics (Bernales et al. [5]),

instantaneous removal of ice shelves (“float-kill”), resolution 64 km,

short steady-state run (\(t=0\ldots{}25\,\mathrm{ka}\)) for modern climate conditions (Fig. 4.2; unpublished).

Fig. 4.2 Ice thickness and surface velocity for the short steady-state simulation for Antarctica with instantaneous removal of ice shelves (“float-kill”), repo_ant64_bm3_ss25ka. The West Antarctic ice sheet has largely disappeared.

Run repo_grl20_b2_paleo21

Greenland ice sheet, SIA, resolution 20 km,

\(t=-140\,\mathrm{ka}\ldots{}0\), basal sliding ramped up during the first 5 ka.

Modified, low-resolution version of the spin-up for ISMIP6 InitMIP (Greve et al. [33]).

Runs repo_grl10_b2_{paleo21, future21_ctrl, future21_asmb}

Greenland ice sheet, SIA, resolution 10 km,

\(t=-9\,\mathrm{ka}\ldots{}0\) for the paleo run, \(t=0\ldots{}100\,\mathrm{a}\) for the two future runs.

10-km version of the spin-up and schematic future climate runs for ISMIP6 InitMIP

(Fig. 4.3; Greve et al. [33], Seroussi et al. [57]).

Fig. 4.3 Ice volume above flotation, expressed in metres of sea-level equivalent (m SLE), for the two ISMIP6 InitMIP future-climate simulations for Greenland, repo_grl10_b2_future21_ctrl (constant-climate control run) and repo_grl10_b2_future21_asmb (schematic surface-mass-balance anomaly applied).

Runs repo_ant64_b2_{spinup09_init100a, spinup09_fixtopo, spinup09, future09_ctrl, future09_asmb, future09_abmb}

Antarctic ice sheet with hybrid shallow-ice–shelfy-stream dynamics

(Bernales et al. [5]) and ice shelves (SSA), resolution 64 km;

\(t=-140.1\ldots{}-140\,\mathrm{ka}\) for the init run without basal sliding (…_init100a),

\(t=-140\,\mathrm{ka}\ldots{}0\) for the run with almost fixed topography (…_fixtopo), basal sliding ramped up during the first 5 ka,

\(t=-0.5\,\mathrm{ka}\ldots{}0\) for the final, freely-evolving-topography part of the spin-up (…_spinup09),

\(t=0\ldots{}100\,\mathrm{a}\) for the three future runs (…_future09_{ctrl, asmb, abmb}).

64-km version of the spin-up and schematic future climate runs for ISMIP6 InitMIP

(Fig. 4.4; Seroussi et al. [57]).

Fig. 4.4 Ice volume above flotation, expressed in metres of sea-level equivalent (m SLE), for the three ISMIP6 InitMIP future-climate simulations for Antarctica, repo_ant64_b2_future09_ctrl (constant-climate control run), repo_ant64_b2_future09_asmb (schematic surface-mass-balance anomaly applied) and repo_ant64_b2_future09_abmb (schematic sub-ice-shelf-melt anomaly applied).

Runs repo_asf2_steady, repo_asf2_surge

Austfonna, SIA, resolution 2 km, \(t=0\ldots{}10\,\mathrm{ka}\).

Similar to Dunse et al. [15]’s Exp. 2 (steady fast flow) and Exp. 5 (surging-type flow), respectively.

Runs repo_nmars10_steady, repo_smars10_steady

North-/south-polar cap of Mars, SIA, resolution 10 km, \(t=-10\,\mathrm{Ma}\ldots{}0\).

Steady-state runs by Greve [29].

Run repo_nhem80_nt012_new

Northern hemisphere, SIA, resolution 80 km, \(t=-250\,\mathrm{ka}\ldots{}0\).

Similar to run nt012 by Greve et al. [40].

Run repo_heino50_st

ISMIP HEINO standard run ST, SIA, resolution 50 km, \(t=0\ldots{}200\,\mathrm{ka}\) (Calov et al. [12]).

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Model times, time steps, computing times:

Run	Model time	Time step†	CPU time
repo_vialov3d25	\(100\,\mathrm{ka}\)	\(20\,\mathrm{a}\)	\(1.0\,\mathrm{min}\)
repo_emtp2sge25_expA	\(200\,\mathrm{ka}\)	\(20\,\mathrm{a}\)	\(4.7\,\mathrm{min}\)
repo_grl16_bm5_ss25ka	\(25\,\mathrm{ka}\)	\(5\,\mathrm{a}\)	\(10.9\,\mathrm{min}\)
repo_grl16_bm5_init100a	\(100\,\mathrm{a}\)	\(5\,\mathrm{a}\)	\(1.6\,\mathrm{sec}\)
repo_grl16_bm5_ss25ka_nudged	\(25\,\mathrm{ka}\)	\(5\,\mathrm{a}\)	\(11.0\,\mathrm{min}\)
repo_ant64_bm3_ss25ka	\(25\,\mathrm{ka}\)	\(2\,/\,10\,\mathrm{a}\)	\(8.9\,\mathrm{min}\)
repo_grl20_b2_paleo21	\(140\,\mathrm{ka}\)	\(5\,\mathrm{a}\)	\(0.9\,\mathrm{hrs}\)
repo_grl10_b2_paleo21*	\(9\,\mathrm{ka}\)	\(1\,\mathrm{a}\)	\(1.1\,\mathrm{hrs}\)
repo_grl10_b2_future21_ctrl	\(100\,\mathrm{a}\)	\(1\,\mathrm{a}\)	\(1.0\,\mathrm{min}\)
repo_grl10_b2_future21_asmb	\(100\,\mathrm{a}\)	\(1\,\mathrm{a}\)	\(1.0\,\mathrm{min}\)
repo_ant64_b2_spinup09_init100a	\(100\,\mathrm{a}\)	\(2\,/\,10\,\mathrm{a}\)	\(4.3\,\mathrm{sec}\)
repo_ant64_b2_spinup09_fixtopo	\(140\,\mathrm{ka}\)	\(3.\bar{3}\,/\,10\,\mathrm{a}\)	\(0.9\,\mathrm{hrs}\)
repo_ant64_b2_spinup09	\(500\,\mathrm{a}\)	\(1\,/\,5\,\mathrm{a}\)	\(0.7\,\mathrm{min}\)
repo_ant64_b2_future09_ctrl	\(100\,\mathrm{a}\)	\(1\,/\,5\,\mathrm{a}\)	\(9.7\,\mathrm{sec}\)
repo_ant64_b2_future09_asmb	\(100\,\mathrm{a}\)	\(1\,/\,5\,\mathrm{a}\)	\(9.7\,\mathrm{sec}\)
repo_ant64_b2_future09_abmb	\(100\,\mathrm{a}\)	\(1\,/\,5\,\mathrm{a}\)	\(10.2\,\mathrm{sec}\)

Table 1: Model times, time steps and computing (CPU) times for the EISMINT, Greenland and Antarctica test simulations contained in the script multi_sico_1.sh, run with SICOPOLIS v24 (revision bdf61628b) and the Intel Fortran compiler 2021.8.0 for Linux (optimization options -xHOST -O3 -no-prec-div) on a single core of a 12-Core Intel Xeon Gold 6256 (3.6 GHz) PC under openSUSE Leap 15.5.

       ^†: If one value is given, this is the common dynamic (velocity, ice thickness) and thermodynamic (temperature, water content, age) time step. If two values, separated by a slash (/), are given, the first one is the dynamic, the second one the thermodynamic time step.

       ^*: For this run, see the remark in the subsection on the resolution-doubler tool.