compass.landice.tests.ismip7_calibration.ais.fit_delta_t.FitDeltaT

class compass.landice.tests.ismip7_calibration.ais.fit_delta_t.FitDeltaT(test_case, melt_forms, state_name='climatology')[source]

A step that fits the basin thermal-forcing correction dT_b.

Protocol Sect. 4.2.1 permits the corrections to be calculated at either stage: (1) before the parameter optimisation, which “can lead to the problem that the parameter bounds are not constrained when present-day melt rates are compared to observations (namely, terms J1 and J2)”; or (2) after it, “as in ISMIP6”. This step follows (2), which is what the published quadratic worked example does, and it is why the calibration itself runs with dT_b = 0 throughout.

dT_b depends on the melt parameter, so it is fitted separately at the 5th, 50th and 95th percentiles of the selected distribution, and a complete MALI parameter file – basins, corrections and the parameter itself – is written for each. Projections at each percentile then need only point at the matching file.

For each basin, dT is searched on a grid within the configured bounds, minimising the absolute difference between the basin-integrated melt and the IMBIE observed value. The protocol recommends bounding dT_b by about 2 K, since the warmest-to-coldest spread across Antarctic ice shelves is only 3-4 K, and recommends avoiding the correction where possible since it is “only an ad-hoc correction”.

The search is done on the MALI mesh with area-weighted integrals. The toolbox’s own optimise_deltaT cannot be used, because it sums over structured-grid x and y dimensions with a single scalar cell area. Melt is recomputed in Python from MALI’s TFdraft, so no further MALI runs are needed: dT enters the melt expression only through the thermal forcing.

Variables:: melt_forms (list of str) – The melt forms to fit dT_b for

__init__(test_case, melt_forms, state_name='climatology')[source]

Create the step

Parameters:

test_case (compass.landice.tests.ismip7_calibration.ais.Ais) – The test case this step belongs to
melt_forms (list of str) – The melt forms to fit dT_b for
state_name (str, optional) – The ocean state to fit against; the present-day climatology, to match the observed present-day melt

Methods

`__init__`(test_case, melt_forms[, state_name])	Create the step
`add_input_file`([filename, target, database, ...])	Add an input file to the step (but not necessarily to the MPAS model).
`add_model_as_input`()	make a link to the model executable and add it to the inputs
`add_namelist_file`(package, namelist[, ...])	Add a file with updates to namelist options to the step to be parsed when generating a complete namelist file if and when the step gets set up.
`add_namelist_options`(options[, out_name, mode])	Add the namelist replacements to be parsed when generating a namelist file if and when the step gets set up.
`add_output_file`(filename)	Add the output file that must be produced by this step and may be made available as an input to steps, perhaps in other test cases.
`add_streams_file`(package, streams[, ...])	Add a streams file to the step to be parsed when generating a complete streams file if and when the step gets set up.
`constrain_resources`(available_resources)	Constrain `cpus_per_task` and `ntasks` based on the number of cores available to this step
`process_inputs_and_outputs`()	Process the inputs to and outputs from a step added with `compass.Step.add_input_file()` and `compass.Step.add_output_file()`.
`run`()	Run this step of the test case
`runtime_setup`()	Update attributes of the step at runtime before calling the `run()` method.
`set_resources`([cpus_per_task, ...])	Update the resources for the subtask.
`setup`()	Set up this step of the test case
`update_namelist_at_runtime`(options[, out_name])	Update an existing namelist file with additional options.
`update_namelist_pio`([out_name])	Modify the namelist so the number of PIO tasks and the stride between them consistent with the number of nodes and cores (one PIO task per node).
`update_streams_at_runtime`(package, streams, ...)	Update the streams files during the run phase of this step using the given template and replacements.