// readme

arl-met

Read, write, subset, and sample NOAA ARL meteorological files.

arl-met provides a Python-first interface to the ARL packed meteorology format used by HYSPLIT and related workflows. It supports:

  • low-level record-preserving reads and writes through File, RecordSet, and DataRecord
  • xarray Dataset reads and common-case writes through open_dataset() and write_dataset(), plus an xarray backend (xr.open_dataset(path, engine="arl"))
  • downloading from NOAA’s ARL archives (HRRR, NAM, GDAS, GFS, …) with optional crop-on-download, and keeping a local mirror complete and checked against NOAA’s MD5 list with Archive.sync()
  • converting other models’ output, opened with xarray, to ARL files (Python versions of HYSPLIT’s data2arl programs): ERA5 on pressure or model levels with converters.from_era5(), GFS and GDAS GRIB2 with converters.from_gfs(), DWD’s ICON-EU and ICON-D2 on their lat/lon grids with converters.from_icon(), WRF output with converters.from_wrf()
  • crop-before-unpack subset extraction with extract_subset()
  • vertical helper functions such as pressure(), z_agl(), and z_msl()
  • point sampling with sample_points()
  • joining files…