Module `local`

This IGM module is designed to load spatial 2D raster data from NetCDF or Tiff files specified by the input_file parameter. The module converts all existing 2D fields (present in the NetCDF file or in the designated folder for Tiff files) into TensorFlow variables. At a minimum, the module is expected to import basal topography represented by the topg variable. Additionally, it completes the data by deriving basal topography from ice thickness and surface topography when necessary. Other fields present will also be converted to TensorFlow variables, allowing them to be accessed in the code via state.myvar. For example, providing the icemask variable can be useful for defining an accumulation area, which is beneficial for modeling individual glaciers and preventing overflow into neighboring catchments.

The module offers functions for resampling the data, where the coarsen parameter can be set to values like 2, 3, or 4 (with a default value of 1 indicating no coarsening). It also supports cropping the data by setting the crop parameter to True and specifying the desired bounds.

Additionally, by setting icemask_invert to True, an ice mask can be generated from an ESRI Shapefile specified by the icemask_shapefile parameter. This mask can identify areas that should contain glaciers or areas that should remain glacier-free, based on the icemask_include parameter.

For marine / tidewater simulations, the water_level sub-config creates a 2D state.water_level field consumed downstream by the iceflow floating energy component (and by thk calving-front schemes). Set water_level.include: True to fill the domain with a uniform value (water_level.value, in metres). If a 2D water_level variable is already present in the input data, it takes precedence and the uniform fill is skipped — letting you prescribe a spatially-varying water level (e.g. a fjord geometry). If water_level is left absent, the flotation term is disabled (the lower surface follows the bed). Note: this used to live in the thk module as default_sealevel and has moved to the input phase, so that state.water_level is available before any process module runs.

The module also supports restarting an IGM run using a NetCDF file produced from a previous IGM run. To achieve this, provide the output NetCDF file from the previous run as input to IGM. The module will seek data corresponding to the starting time defined by processes.time.start and initialize the simulation at that time.

This module depends on the xarray and rioxarray Python libraries.

Contributors: B. Finley, A. Henz (icemask add-on), G. Jouvet (tif format).

Parameters

Default configuration file (local.yaml):

local:
  type: netcdf
  filename: input.nc
  coarsening:
    boundary: trim
    ratio: 1.0
  crop:
    xmin: null
    xmax: null
    ymin: null
    ymax: null
  icemask:
    include: False
    shapefile: icemask.shp
    invert: False
  water_level:
    include: False
    value: 0.0

Description of the parameters:

Name	Description	Default value	Units
`type`	Type of file to be loaded, can be netcdf or tif.	netcdf	—
`filename`	NetCDF input data file.	input.nc	—

coarsening

Name	Description	Default value	Units
`coarsening.boundary`	Method for coarsening the data from NetCDF file: skipping or cubic_spline.	trim	—
`coarsening.ratio`	Coarsen ratio.	1.0	—

crop

Name	Description	Default value	Units
`crop.xmin`	X left coordinate for cropping the NetCDF data.	None	m
`crop.xmax`	X right coordinate for cropping the NetCDF data.	None	m
`crop.ymin`	Y bottom coordinate for cropping the NetCDF data.	None	m
`crop.ymax`	Y top coordinate for cropping the NetCDF data.	None	m

icemask

Name	Description	Default value	Units
`icemask.include`	Include ice mask in the NetCDF file.	False	—
`icemask.shapefile`	Shapefile for ice mask.	icemask.shp	—
`icemask.invert`	Invert the ice mask.	False	—

water_level

Name	Description	Default value	Units
`water_level.include`	Create a uniform 2D `state.water_level` field. Only applied if `water_level` is not already loaded from the input data. Required by the iceflow `floating` energy component for marine / tidewater setups.	False	—
`water_level.value`	Value (in metres) used to fill the uniform `water_level` field when `include: True`.	0.0	m

Module local

Parameters

Module `local`