add_reconstruction_weights

utils/omega/add_reconstruction_weights.py is a standalone script that computes edge vector reconstruction weights and appends them to an existing MPAS-Ocean or Omega mesh file.

The weights are computed using the least-squares method described in Peixoto and Barros (2014) using a two-ring edge stencil (see Figure 5 of that paper).

The script auto-detects whether the input file uses MPAS-Ocean or Omega naming conventions and writes output in the same convention. compute_reconstruction_weights() internally selects only the small mesh/grid variables needed for the calculation, so large state/tracer fields are never loaded, making it safe to run on production meshes.

Usage

./utils/omega/add_reconstruction_weights.py \
    -i <input_mesh.nc> \
    -o <output_mesh.nc>

Flag	Description
`-i` / `--input_file`	Input mesh file (MPAS-Ocean or Omega format)
`-o` / `--output_file`	Output file (copy of input with weights appended)

For production-sized meshes (e.g. 6to18km) the script should be run on a compute node. Since the mesh connectivity information needed to compute the weights fits into memory, the reconstruction weights are computed serially using numpy/xarray, as recommended by Dask best practices.