For reasons I won’t go into i’m looking to regrid lat-lon data to N640 (N640 | ECMWF).
The best way to work with N640 is likely a flat array such as that used in gs://gcp-public-data-arco-era5/co/single-level-reanalysis.zarr which is N320 (N320 | ECMWF) also see arco-era5/0-Surface-Reanalysis-Walkthrough.ipynb at main · google-research/arco-era5 · GitHub
I haven’t found any libraries which can help. regrid — metview documentation may only have spectral to lat-lon regridded but not the inverse