API Reference#

Use this reference when you want the exact signature, parameters, return values, and class interfaces for arl-met. Most workflows start with open_dataset(), write_dataset(), extract_subset(), or sample_points().

High-Level I/O#

`open_dataset`	Open an ARL meteorology file as an xarray Dataset.
`write_dataset`	Write a simple flat Dataset representation to an ARL file.

File Operations#

Transform ARL files: crop a subset, sample at points, or join files together. See the Cropping ARL Data, Sampling Points, and Concatenating ARL Files guides.

`extract_subset`	Extract a spatial/vertical subset from an ARL file into a new ARL file.
`sample_points`	Sample meteorological variables at arbitrary (lon, lat, z, time) points.
`concat`	Concatenate multiple ARL files into a single ARL file.
`concat_by_time`	Group every ARL file in a directory by valid time and concatenate each group.

Vertical Coordinates#

Derive pressure and height coordinates from an open Dataset. See the Vertical Coordinates guide for coordinate-system details and limitations.

`pressure`	Pressure (hPa) at each level.
`z_agl`	Height above ground level (m) at each level.
`z_msl`	Height above mean sea level (m) at each level.

Low-Level File Model#

`File`	Read or write an ARL meteorology file.
`RecordSet`	Records for one valid time within an ARL file.
`DataRecord`	One ARL data record representing a single 2D variable slice.

Grid And Vertical Metadata#

These are immutable, hashable value objects. Derive modified copies with dataclasses.replace() (Projection, Grid, GridWindow) or by constructing a new axis.

`Projection`	Horizontal projection metadata from an ARL index record.
`Grid`	Two-dimensional horizontal grid definition for ARL data.
`GridWindow`	Rectangular subset of a grid using zero-based half-open indices.
`VerticalAxis`	Abstract base class for ARL vertical coordinate axes.
`SigmaAxis`	Flag=1.
`PressureAxis`	Flag=2.
`TerrainAxis`	Flag=3.
`HybridAxis`	Flag=4.

Binary Metadata And Packing#

`Header`	Fixed-width 50-byte header present at the start of every ARL record.
`IndexRecord`	Index record describing one ARL time step and its contained variables.
`calculate_checksum`	Compute the ARL checksum for a packed payload.
`pack`	Pack a 2D field using the ARL differential byte encoding.
`unpack`	Unpack an ARL differential byte stream into a 2D field.

Errors And Warnings#

Raised or emitted when file content is not valid ARL. ARLFormatError subclasses ValueError, so except ValueError also catches it.

`ARLFormatError`	Raised when file content is not valid ARL.
`ARLFormatWarning`	Warning for recoverable irregularities in ARL file content.

Remote Archive Sources#

`get_archive`	Build a meteorology archive from its short name.
`Archive`	Abstract base class for NOAA ARL meteorology archives.
`HRRRArchive`	HRRR 3 km analysis (CONUS, June 2019–present).
`HRRRv1Archive`	HRRR 3 km analysis, version 1 (CONUS, June 15, 2015–2019).
`NAMArchive`	NAM 12 km analysis (North America, May 26, 2007–present).
`NAMSArchive`	NAMS hybrid sigma-pressure analysis (CONUS/Alaska/Hawaii, March 2009–present).
`GDASArchive`	GDAS 1-degree global analysis (December 2004–present).
`GDAS0p5Archive`	GDAS 0.5-degree global analysis (September 2007–mid 2019).
`GFSArchive`	GFS 0.25-degree global analysis (June 13, 2019–present).
`NARRArchive`	NCEP North American Regional Reanalysis (January 1979–2019).
`ReanalysisArchive`	NCEP/NCAR Reanalysis 2.5-degree global (1948–present).

arlmet.archives.ARCHIVES: Every registered source class by name (read-only mapping). See get_archive().