Watching the first run¶
As soon as the run starts it creates time-dependent NetCDF files
ex_g20km_10ka.nc. The latter file, which has spatially-dependent fields at each time,
is created after the first 100 model years, a few wall clock seconds in this case. The
-extra_file ex_g20km_10ka.nc -extra_times -10000:100:0 adds a
spatially-dependent “frame” at model times -9900, -9800, …, 0.
To look at the spatial-fields output graphically, do:
We see that
ex_g20km_10ka.nc contains growing “movies” of the fields chosen by the
-extra_vars option. A frame of the ice thickness field
thk is shown in
Fig. 2 (left).
The time-series file
ts_g20km_10ka.nc is also growing. It contains spatially-averaged
“scalar” diagnostics like the total ice volume or the ice-sheet-wide maximum velocity
max_hor_vel, respectively). It can be viewed by
The growing time series for
ice_volume_glacierized is shown in Fig. 2
(right). Recall that our intention was to generate a minimal model of the Greenland ice
sheet in approximate steady-state with a steady (constant-in-time) climate. The measurable
steadiness of the
ice_volume_glacierized time series is a possible standard for steady
state (see , for exampe).
thk, the ice sheet thickness, a space-dependent field, from file
ice_volume_glacierized, the total ice sheet volume time-series, from file
At the end of the run the output file
g20km_10ka.nc is generated.
Fig. 3 shows some fields from this file. In the next subsections we
consider their “quality” as model results. To see a report on computational performance,
ncdump -h g20km_10ka.nc |grep history :history = "user@machine 2017-10-04 19:16:08 AKDT: PISM done. Performance stats: 0.1784 wall clock hours, 0.7136 proc.-hours, 14005.0054 model years per proc.-hour.\n",
usurf, the ice sheet surface elevation in meters.
velsurf_mag, the surface speed in meters/year, including the 100 m/year contour (solid black).
mask, with 0 = ice-free land, 2 = grounded ice, 4 = ice-free ocean.