run_inversion.py

This script will perform ice thickness inversion while calibrating the ice viscosity (“Glen A”) model parameter such that the modeled ice volume roughly matches the ice volume estimates from Farinotti et al. (2019) for each RGI region. Run the script as follows:

run_inversion -rgi_region01 <region>

Script Structure

Broadly speaking, the script follows:

• Load glaciers

• Load climate data

• Compute apparent mass balance and invert for initial ice thickness

• Use minimization to find agreement between our modeled and Farinotti et al. (2019) modeled ice thickness estimates for each RGI region

• Export the calibrated parameters

Special Considerations

The regional Glen A value is calibrated by inverting for the ice thickness of all glaciers in a given region without considering calving (all glaciers are considered land-terminating). After the “best” Glen A value is determined, a final round of ice thickness inversion is performed for tidewater glaciers with calving turned on. Running this script will by default export the regionally calibrated Glen A values to the path specfied by sim.oggm_dynamics.glen_a_regional_relpath in ~/PyGEM/config.yaml’. The calibrated inversion parameters also get stored within a given glacier directories diagnostics.json file, e.g.:

{"dem_source": "COPDEM90", "flowline_type": "elevation_band", "apparent_mb_from_any_mb_residual": 2893.2237556771674, "inversion_glen_a": 3.784593106855888e-24, "inversion_fs": 0}