Index NAQFC AQM (v7) O3 and PM2.5 72 Hour Forecasts

[siddharth0248]

Dataset: NOAA National Air Quality Forecast Capability (NAQFC) Regional Model Guidance: Air Quality Model (AQM) v7 - O3 and PM2.5 72 Hour Forecasts

Dataset: availble in public bucket
Format: GRIB2
Potential Use Case: titiler-multidim

Access link: registry.opendata.aws/noaa-nws-naqfc-pds

Data can be visualized here

[siddharth0248]

https://github.com/Air-Quality-Portal/aq-arch/issues/100

[siddharth0248]

@abarciauskas-bgse

import xarray as xr

# Path to your GRIB2 file
grib_file = "aqm.t12z.ave_1hr_o3.20240514.227.grib2"

# Open the dataset
ds = xr.open_dataset(
    grib_file,
    engine="cfgrib"
)

print(ds)

<xarray.Dataset> Size: 459MB
Dimensions:     (step: 72, y: 1025, x: 1473)
Coordinates:
  * step        (step) timedelta64[ns] 576B 01:00:00 ... 3 days 00:00:00
    time        datetime64[ns] 8B ...
    sigma       float64 8B ...
    latitude    (y, x) float64 12MB ...
    longitude   (y, x) float64 12MB ...
    valid_time  (step) datetime64[ns] 576B ...
Dimensions without coordinates: y, x
Data variables:
    ozcon       (step, y, x) float32 435MB ...
Attributes:
    GRIB_edition:            2
    GRIB_centre:             kwbc
    GRIB_centreDescription:  US National Weather Service - NCEP
    GRIB_subCentre:          0
    Conventions:             CF-1.7
    institution:             US National Weather Service - NCEP
    history:                 2026-06-25T14:45 GRIB to CDM+CF via cfgrib-0.9.1...

print(ds.attrs)

{'GRIB_edition': 2, 'GRIB_centre': 'kwbc', 'GRIB_centreDescription': 'US National Weather Service - NCEP', 'GRIB_subCentre': 0, 'Conventions': 'CF-1.7', 'institution': 'US National Weather Service - NCEP', 'history': '2026-06-25T14:45 GRIB to CDM+CF via cfgrib-0.9.15.1/ecCodes-2.44.0 with {"source": "aqm.t12z.ave_1hr_o3.20240514.227.grib2", "filter_by_keys": {}, "encode_cf": ["parameter", "time", "geography", "vertical"]}'}

print(ds["ozcon"].attrs)

{'GRIB_paramId': 260379, 'GRIB_dataType': 'fc', 'GRIB_numberOfPoints': 1509825, 'GRIB_typeOfLevel': 'sigma', 'GRIB_stepUnits': 1, 'GRIB_stepType': 'avg', 'GRIB_gridType': 'lambert', 'GRIB_uvRelativeToGrid': 1, 'GRIB_DxInMetres': 5079.0, 'GRIB_DyInMetres': 5079.0, 'GRIB_LaDInDegrees': 25.0, 'GRIB_Latin1InDegrees': 25.0, 'GRIB_Latin2InDegrees': 25.0, 'GRIB_LoVInDegrees': 265.0, 'GRIB_NV': 0, 'GRIB_Nx': 1473, 'GRIB_Ny': 1025, 'GRIB_cfName': 'unknown', 'GRIB_cfVarName': 'ozcon', 'GRIB_gridDefinitionDescription': 'Lambert Conformal can be secant or tangent, conical or bipolar', 'GRIB_iScansNegatively': 0, 'GRIB_jPointsAreConsecutive': 0, 'GRIB_jScansPositively': 1, 'GRIB_latitudeOfFirstGridPointInDegrees': 12.19, 'GRIB_latitudeOfSouthernPoleInDegrees': -90.0, 'GRIB_longitudeOfFirstGridPointInDegrees': 226.541, 'GRIB_longitudeOfSouthernPoleInDegrees': 0.0, 'GRIB_missingValue': 3.4028234663852886e+38, 'GRIB_name': 'Ozone Concentration (PPB)', 'GRIB_shortName': 'ozcon', 'GRIB_units': 'ppb', 'long_name': 'Ozone Concentration (PPB)', 'units': 'ppb', 'standard_name': 'unknown'}

print(ds.coords)

Coordinates:
  * step        (step) timedelta64[ns] 576B 01:00:00 ... 3 days 00:00:00
    time        datetime64[ns] 8B ...
    sigma       float64 8B ...
    latitude    (y, x) float64 12MB ...
    longitude   (y, x) float64 12MB ...
    valid_time  (step) datetime64[ns] 576B ...

for k, v in sorted(ds["ozcon"].attrs.items()):
    print(f"{k}: {v}")

GRIB_DxInMetres: 5079.0
GRIB_DyInMetres: 5079.0
GRIB_LaDInDegrees: 25.0
GRIB_Latin1InDegrees: 25.0
GRIB_Latin2InDegrees: 25.0
GRIB_LoVInDegrees: 265.0
GRIB_NV: 0
GRIB_Nx: 1473
GRIB_Ny: 1025
GRIB_cfName: unknown
GRIB_cfVarName: ozcon
GRIB_dataType: fc
GRIB_gridDefinitionDescription: Lambert Conformal can be secant or tangent, conical or bipolar
GRIB_gridType: lambert
GRIB_iScansNegatively: 0
GRIB_jPointsAreConsecutive: 0
GRIB_jScansPositively: 1
GRIB_latitudeOfFirstGridPointInDegrees: 12.19
GRIB_latitudeOfSouthernPoleInDegrees: -90.0
GRIB_longitudeOfFirstGridPointInDegrees: 226.541
GRIB_longitudeOfSouthernPoleInDegrees: 0.0
GRIB_missingValue: 3.4028234663852886e+38
GRIB_name: Ozone Concentration (PPB)
GRIB_numberOfPoints: 1509825
GRIB_paramId: 260379
GRIB_shortName: ozcon
GRIB_stepType: avg
GRIB_stepUnits: 1
GRIB_typeOfLevel: sigma
GRIB_units: ppb
GRIB_uvRelativeToGrid: 1
long_name: Ozone Concentration (PPB)
standard_name: unknown
units: ppb

for k, v in sorted(ds["ozcon"].attrs.items()):
    if k.startswith("GRIB_"):
        print(f"{k}: {v}")

GRIB_DxInMetres: 5079.0
GRIB_DyInMetres: 5079.0
GRIB_LaDInDegrees: 25.0
GRIB_Latin1InDegrees: 25.0
GRIB_Latin2InDegrees: 25.0
GRIB_LoVInDegrees: 265.0
GRIB_NV: 0
GRIB_Nx: 1473
GRIB_Ny: 1025
GRIB_cfName: unknown
GRIB_cfVarName: ozcon
GRIB_dataType: fc
GRIB_gridDefinitionDescription: Lambert Conformal can be secant or tangent, conical or bipolar
GRIB_gridType: lambert
GRIB_iScansNegatively: 0
GRIB_jPointsAreConsecutive: 0
GRIB_jScansPositively: 1
GRIB_latitudeOfFirstGridPointInDegrees: 12.19
GRIB_latitudeOfSouthernPoleInDegrees: -90.0
GRIB_longitudeOfFirstGridPointInDegrees: 226.541
GRIB_longitudeOfSouthernPoleInDegrees: 0.0
GRIB_missingValue: 3.4028234663852886e+38
GRIB_name: Ozone Concentration (PPB)
GRIB_numberOfPoints: 1509825
GRIB_paramId: 260379
GRIB_shortName: ozcon
GRIB_stepType: avg
GRIB_stepUnits: 1
GRIB_typeOfLevel: sigma
GRIB_units: ppb
GRIB_uvRelativeToGrid: 1

Key observations

• Single science variable: ozcon (Ozone Concentration)
• 72 hourly forecast steps
• Spatial grid size: 1473 × 1025
• Latitude and longitude are provided as 2D coordinate arrays
• Dataset follows CF-1.7 conventions.
• GRIB_gridType = lambert