cfdb-ingest 0.1.2

File format conversions to cfdb

cfdb-ingest

Convert meteorological model output to cfdb with standardized CF conventions

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Documentation: https://mullenkamp.github.io/cfdb-ingest/

Source Code: https://github.com/mullenkamp/cfdb-ingest

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Table of Contents

• Overview
• Supported Formats
• WRF Variables
• Installation
• Python API
• CLI
• Development
• License

Overview

cfdb-ingest converts meteorological file formats (netCDF4/HDF5, GRIB2, etc.) from various model outputs into cfdb. It standardizes variable names and attributes to be consistent with CF conventions, making it straightforward to work with datasets from different sources through a single interface.

Key features:

• Automatic variable mapping -- source variable names are translated to CF-standard names with proper metadata (standard_name, units, encoding)
• Wind rotation -- grid-relative wind components are rotated to earth-relative using COSALPHA/SINALPHA
• 3D level interpolation -- eta-level variables are interpolated to user-specified height levels above ground
• Variable merging -- surface and level-interpolated variants of the same quantity (e.g. T2 at 2 m and T at arbitrary heights) are merged into a single output variable
• Spatial and temporal filtering -- subset by bounding box (WGS84) and/or date range before writing
• Multi-file support -- seamlessly spans multiple input files, including cross-file precipitation accumulation
• Configurable chunking -- tune output chunk shapes for different access patterns

Supported Formats

Source	Class	CRS Projections
WRF (wrfout)	WrfIngest	Lambert Conformal Conic, Polar Stereographic, Mercator, Lat-Lon

WRF Variables

Surface variables (fixed height above ground):

Key	cfdb Name	Height	Source Vars	Transform
T2	air_temp	2 m	T2	direct
PSFC	surface_pressure	0 m	PSFC	direct
Q2	specific_humidity	2 m	Q2	direct
RAIN	precip	0 m	RAINNC, RAINC	accumulation increment
WIND10	wind_speed	10 m	U10, V10	wind rotation
WIND_DIR10	wind_direction	10 m	U10, V10	wind rotation
U10	u_wind	10 m	U10, V10	wind rotation
V10	v_wind	10 m	U10, V10	wind rotation
TSK	soil_temp	0 m	TSK	direct
SWDOWN	shortwave_radiation	0 m	SWDOWN	direct
GLW	longwave_radiation	0 m	GLW	direct
SNOWH	snow_depth	0 m	SNOWH	direct
SLP	mslp	0 m	PSFC, T2, HGT	hypsometric reduction

3D level-interpolated variables (interpolated to user-specified target_levels):

Key	cfdb Name	Source Vars	Transform
T	air_temp	T, P, PB, PH, PHB	potential to actual temperature
WIND	wind_speed	U, V, PH, PHB	unstagger + rotation
WIND_DIR	wind_direction	U, V, PH, PHB	unstagger + rotation
U	u_wind	U, V, PH, PHB	unstagger + rotation
V	v_wind	U, V, PH, PHB	unstagger + rotation
Q	specific_humidity	QVAPOR, PH, PHB	mixing ratio to specific humidity

Installation

Requires Python >= 3.11.

pip install cfdb-ingest

Python API

Basic conversion

from cfdb_ingest import WrfIngest

wrf = WrfIngest('wrfout_d01_2023-02-12_00:00:00.nc')

# Convert selected variables for a time window
wrf.convert(
    cfdb_path='output.cfdb',
    variables=['T2', 'WIND10', 'precip'],
    start_date='2023-02-12T06:00',
    end_date='2023-02-12T18:00',
)

Multi-file input

wrf = WrfIngest([
    'wrfout_d01_2023-02-12_00:00:00.nc',
    'wrfout_d01_2023-02-13_00:00:00.nc',
])

# All timesteps across both files are merged automatically
wrf.convert(cfdb_path='output.cfdb', variables=['T2'])

Spatial subsetting with a bounding box

wrf.convert(
    cfdb_path='output.cfdb',
    variables=['T2'],
    bbox=(165.0, -47.0, 175.0, -40.0),  # (min_lon, min_lat, max_lon, max_lat)
)

3D level interpolation

# Interpolate 3D temperature and wind to specific heights above ground
wrf.convert(
    cfdb_path='output.cfdb',
    variables=['T', 'WIND'],
    target_levels=[100.0, 500.0, 1000.0, 2000.0],
    bbox=(165.0, -47.0, 175.0, -40.0),
)

Merging surface and 3D variables

Variables sharing a cfdb name are automatically merged. For example, T2 (2 m) and T (levels) both map to air_temp and produce a single output variable spanning all heights:

wrf.convert(
    cfdb_path='output.cfdb',
    variables=['T2', 'T'],
    target_levels=[100.0, 500.0],
)
# Output height coordinate: [2.0, 100.0, 500.0]

Custom chunk shape

The output chunk shape defaults to (1, 1, ny, nx) (one full spatial slab per timestep per height level). Override it for different access patterns:

wrf.convert(
    cfdb_path='output.cfdb',
    variables=['T2'],
    chunk_shape=(1, 1, 50, 50),  # (time, z, y, x)
)

Inspecting metadata before conversion

wrf = WrfIngest('wrfout_d01_2023-02-12_00:00:00.nc')

wrf.crs                # pyproj.CRS
wrf.times              # numpy datetime64 array
wrf.x, wrf.y           # 1D projected coordinate arrays
wrf.variables          # dict of available variable mappings
wrf.bbox_geographic    # (min_lon, min_lat, max_lon, max_lat)

Variable name resolution

variables accepts mapping keys (T2), source variable names (RAINNC), or cfdb names (air_temp). When a cfdb name maps to multiple keys, all are included:

wrf.resolve_variables(['air_temp'])  # ['T2', 'T']
wrf.resolve_variables(['RAINNC'])    # ['RAIN']
wrf.resolve_variables(None)          # all available keys

CLI

cfdb-ingest provides a cfdb-ingest command with a wrf subcommand.

Basic usage

cfdb-ingest wrf wrfout_d01_2023-02-12_00:00:00.nc output.cfdb \
    -v T2,WIND10 \
    -s 2023-02-12T06:00 \
    -e 2023-02-12T18:00

All options

cfdb-ingest wrf [OPTIONS] INPUT_PATHS... CFDB_PATH

Option	Short	Description
--variables	-v	Comma-separated variable names
--start-date	-s	Start date (ISO format)
--end-date	-e	End date (ISO format)
--bbox	-b	Bounding box: min_lon,min_lat,max_lon,max_lat
--target-levels	-l	Comma-separated height levels in meters
--chunk-shape	-c	Output chunk shape: time,z,y,x (e.g. 1,1,50,50)
--max-mem		Read buffer size in bytes (default: 128 MiB)
--compression		Compression algorithm: zstd or lz4

Examples

# Convert with spatial subset
cfdb-ingest wrf wrfout_d01_*.nc output.cfdb \
    -v T2 -b 165.0,-47.0,175.0,-40.0

# 3D temperature at specific height levels
cfdb-ingest wrf wrfout_d01_*.nc output.cfdb \
    -v T -l 100,500,1000,2000 -b 165.0,-47.0,175.0,-40.0

# Custom chunk shape for time-series access patterns
cfdb-ingest wrf wrfout_d01_*.nc output.cfdb \
    -v T2,WIND10 -c 24,1,50,50

Development

Setup environment

We use UV to manage the development environment and production build.

uv sync

Run tests

uv run pytest

Lint and format

uv run lint

License

This project is licensed under the terms of the Apache Software License 2.0.