ensemble_generator test group (
creates an ensemble of MALI
simulations with different parameter values. The ensemble framework
sets up a user-defined number of simulations with parameter values selected
by uniform sampling or from a space-filling Sobol sequence
The shared config options for the
ensemble_generator test group are described
in ensemble_generator in the User’s Guide.
defines a step for a single ensemble member (model run). The constructor
stores the run number and name, as well as the parameter values to be used
and the python package where the namelist, streams, and albany input file
can be found. By setting up an
ensemble_member this way, this class can
be flexibly called from any ensemble test case variants that one would like
to define in the future.
setup method actually sets up the run by first setting up a baseline
configuration and then modifying parameter values using the parameter
values defined when the constructor was called. There are operations to set
basal friction exponent
scaling factor on muFriction
scaling factor on stiffnessFactor
von Mises threshold stress
calving speed limit
gamma0 melt sensitivity parameter in ISMIP6-AIS ice-shelf basal melting parameterization
target ice-shelf basal melt rate for ISMIP6-AIS ice-shelf basal melting parameterization. In the model setup, the deltaT thermal forcing bias adjustment is adjusted to obtain the target melt rate for a given gamma0
Each parameter can be activated or disabled as a free parameter. If disabled, whatever values specified in namelist and input files will be used.
Because changing the exponent requires modifying the input file to adjust muFriction to yield the same basal shear stress as the original file, there is also an operation to set the output filename in the streams file, where the file to be used and modified was specified in the cfg file for the test case. The default input file is renamed to indicate it was modified. This is updated automatically in the streams file, and it seeks to avoid potential confusion if a user were to use this file for another purpose.
Similarly, because changing gamma0 and deltaT require modifying a basal melt parameter file, the baseline file path needs to be specified in the config and that file is copied, renamed, and modified in each run directory.
Additionally, a job script is written for the run so that the run can be submitted as a slurm job independent of other runs in the ensemble. This also allows a user to easily run a single ensemble member by submitting the job script within the run step work directory.
Finally, a symlink to the compass load script is added to the run work directory, which compass does not do by default.
run method creates a graph file and runs MALI.
There is a function
_adjust_friction_exponent that modifies the
friction exponent in the
albany_input.yaml file and adjusts muFriction
in the input file to maintain an unchanged basal shear stress. Similarly,
there is a function
_adjust_basal_melt_params that modifes gamma0 and
deltaT in a basal melt parameter file.
defines a step for managing the entire ensemble. The constructor and setup
methods perform minimal operations. The
run method submits each run in
the ensemble as a slurm job. Eventually the
ensemble_manager will be able
to assess if runs need restarts and modify them to be submitted as such.
uses the framework described above to set up an ensemble of
simulations. The constructor simply adds the ensemble manager as the only step.
This allows the test case to be listed by
compass list without having all
ensemble members listed in a verbose listing. Because there may be dozens of
ensemble members, it is better to wait to have them added until the setup
phase. Also, by waiting until configure to define the ensemble members, it
is possible to have the start and end run numbers set in the config,
because the config is not parsed by the constructor.
configure method is where most of the work happens. Here, the start
and end run numbers are read from the config, a parameter array is generated,
and the parameters to be varied and over what range are defined.
The values for each parameter are
passed to the
EnsembleMember constructor to define each run.
Finally, each run is now added to the test case as a step to run,
because they were not automatically added by compass during the test
case constructor phase.
There are no
validate steps required. The ensemble manager
handles “running” ensemble members by submitting them as slurm jobs.
This is a major difference in how this test case functions from most
compass test cases.
The visualization script
plot_ensemble.py is symlinked in the test
case work directory and can be run manually to assess the status of the
ensemble, but there is not a formal analysis step that can be run through