Generating test files

ismip7-generate-test-files creates ISMIP7-style NetCDF test files with synthetic data, one file per variable, following the naming convention and grid definitions used by the compliance checker. It is part of the isschecker package (isschecker.generate), so it is installed along with the checker — conda create -n isschecker -c conda-forge isschecker, see Installation — and can be run from any directory.

Files are written to Models/{GrIS|AIS}/ISMIP7/SYNTH1/CORE/{set_counter}/ (default C001) beneath the current working directory.

Usage

conda activate isschecker
ismip7-generate-test-files [OPTIONS]

Key options

Option	Default	Description
--grid	GrIS_16000m	Grid to use (run --list-grids to see all available)
--scenario	ctrl	Experiment name written into filenames and the time axis
--start-year	2015	First year of the time axis
--nyears	5	Number of annual time steps
--xyt	off	Include x,y,t (3D) variables
--scalars	off	Include scalar (time-only) variables
--include-non-mandatory	off	Also generate non-mandatory variables
--ism-member-id	m001	ISM ensemble member id (written into filenames)
--esm-id	CESM2-WACCM	ESM id (written into filenames)
--forcing-member-id	f001	Forcing ensemble member id (written into filenames)
--set-counter	C001	Set counter id (written into filenames)
--seed	0	Seed for the synthetic data; the same seed always produces the same values
--list-grids	—	List all available grids and exit

Examples

# List available grids
ismip7-generate-test-files --list-grids

# Generate 286-year GrIS ctrl files (x,y,t variables)
ismip7-generate-test-files --grid GrIS_16000m --scenario ctrl \
  --xyt --nyears 286 --start-year 2015

# Generate 286-year AIS ssp370 files
ismip7-generate-test-files --grid AIS_08000m --scenario ssp370 \
  --xyt --nyears 286 --start-year 2015

# Generate scalar-only variables
ismip7-generate-test-files --grid GrIS_16000m --scenario ctrl \
  --scalars --nyears 286 --start-year 2015

# Generate both 3D and scalar variables, including non-mandatory ones
ismip7-generate-test-files --grid GrIS_16000m --scenario ctrl \
  --xyt --scalars --include-non-mandatory --nyears 286 --start-year 2015

# Generate testdata for ismip7-scalar-processing
ismip7-generate-test-files --grid AIS_16000m --scenario historical \
  --set-counter C001 --xyt --include-non-mandatory --nyears 1  --start-year 2014 
ismip7-generate-test-files --grid AIS_16000m --scenario ssp585 \
  --set-counter C007 --xyt --include-non-mandatory --nyears 286 --start-year 2015
ismip7-generate-test-files --grid GrIS_16000m --scenario historical \
  --set-counter C001 --xyt --include-non-mandatory --nyears 55  --start-year 1960
ismip7-generate-test-files --grid GrIS_16000m --scenario ctrl \
  --set-counter C009 --xyt --include-non-mandatory --nyears 286 --start-year 2015

Implemented conventions

• CF-1.7 as baseline.

• Time encoding: days since 1850-01-01, calendar='standard'.

  • State (ST) variables: timestamp is Jan 1 of year N+1 (end-of-year snapshot). No time_bounds.

  • Flux (FL) variables: timestamp is Jul 1 of year N (mid-year), with time_bounds = [Jan 1 of N, Jan 1 of N+1].

  • x,y,z,t variables (e.g. litemp): ST snapshots at a sparse set of nominal years. For historical: first year of run, 1900 (if in range), last year of run. For projection scenarios: 2100, 2200, 2300 (each if within the simulation year range). The filename year range reflects the full simulation period, not the first/last snapshot year. The set is CENTURY_SNAPSHOT_YEARS in isschecker.checker, imported here so the generator and the checker cannot disagree; note that no snapshot is written at 2000, which the checker accepts but does not require (see Time encoding).

• An analytic ice sheet, so that the files agree with one another. Most variables are still drawn at random within the min/max range the data request allows them, but seven cannot be: sftgif, sftgrf, sftflf, lithk, topg, base and orog are computed from a radially symmetric dome on a bowl-shaped bed, because the checker compares them against each other and a random thickness does not agree with a random mask about where the ice is. The identities hold exactly rather than to a tolerance: grounded plus floating fraction is the ice fraction, thickness is positive exactly where the ice fraction is, surface elevation is base plus thickness, and the ice base rests on the bed where the ice is grounded and above it where it floats. The geometry is deliberately analytic rather than taken from BedMachine or Bedmap: a synthetic file’s job is to be predictable, and depending on one dataset would invite depending on datasets for everything else.

• Missing values follow each variable’s fill_policy. A variable the request defines only where there is ice is written as the fill value wherever the ice fraction is zero, and likewise for grounded-only and floating-only variables; the ones defined only inside the computational domain are missing outside it; and the rest are defined everywhere.

• Single precision (float32) for all variables and time.

• _FillValue and missing_value set to NetCDF4 default f4 fill value.

• time is an unlimited (record) dimension.

• x and y are 1-D coordinate variables in meters.

• CRS set per domain: GrIS → EPSG:3413, AIS → EPSG:3031.

Notes

• Variable metadata is read from ISMIP7_variable_request.csv and grid definitions from gdfs/, both bundled as package data in isschecker/data/. Use --conventions-dir to point at a different directory (it must contain the CSV and a gdfs/ subdirectory).

• group, model, contact_name, and contact_email are hardcoded in create_netcdf_file() to synthetic defaults — edit there to customize.

• Generated files are synthetic and intended for testing the compliance checker, not for scientific use.

• Data values are drawn from a seeded generator, so a given --seed reproduces the same files. With --multiple, each file uses seed + i so the files differ from one another while the run as a whole stays reproducible.