Tools

Tools#

This project includes a small collection of helper scripts under src/CHM/tools. They cover data conversion, validation, and preprocessing tasks commonly needed when working with CHM outputs or inputs.

chm_ugrid2grid#

Convert CHM UGRID NetCDF files to structured GeoTIFF or Zarr outputs using ESMF regridding. Input can be NetCDF, a Zarr store directory, or a kerchunk reference file (json/yaml). Zarr/kerchunk inputs require --mesh pointing to a NetCDF UGRID mesh topology file.

Example:

chm_ugrid2grid input.nc --dxdy 0.01 --method conservative \
    --tiff-output ./tiffs --zarr-output ./zarr --overwrite

Key options:

  • --mesh: load mesh topology from a separate NetCDF file.

  • --variables: limit conversion to the listed variables.

  • --timeoffset: pick specific time indices to process.

  • --zarr-chunk-y / --zarr-chunk-x: tune Zarr chunk sizes.

  • --overwrite: allow replacing existing outputs.

chm_pvd_from_dir#

Create an out.pvd ParaView Data file by scanning *.vtu files in the current directory. Assumes filenames follow <prefix><timestamp>_<rank>.vtu.

Usage:

chm_pvd_from_dir

chm_validateJSON#

Simple syntax check for CHM JSON configuration files. Reports whether the input parses without validating content semantics.

Usage:

chm_validateJSON config.json

chm_windmapper2mesher#

Generate a config_WN.txt mapping for CHM’s mesher from a directory of WindNinja/Windmapper GeoTIFFs.

Usage:

chm_windmapper2mesher /path/to/windmapper/tiles

The script inspects directional tiles (*_U.tif, *_V.tif, *spd_up*.tif), derives available wind directions, and writes Ninja variable entries for each.

chm_build_multipart_nc#

Create a JSON manifest describing a set of meteorological NetCDF files that CHM should read sequentially for forcing.

Usage:

chm_build_multipart_nc /path/to/met_chunks

This scans the provided directory for *.nc files, records each file’s time coverage (start/end) and absolute path, and writes metdata-<folder>.json to the current working directory. Pass that JSON to CHM in place of a single met file to enable multipart forcing.

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