libera_utils.footprint_matching.readers.brdf#

VIIRS surface BRDF reader plugin for the footprint matching pipeline.

Data source: VIIRS/NOAA-20 BRDF/Albedo Model Parameters Daily L3 Global 0.05° CMG

  • Product: VJ143C1 (Collection 002)

  • Format: HDF5/HDF-EOS5 (.h5), opened via h5py

  • Spatial resolution: 0.05° (~5.6 km at equator)

  • Grid: 3600 × 7200 global Climate Model Grid (CMG). The file’s lat/lon hold each cell’s upper-left edge, latitude DESCENDING (90 → −89.95, longitude −180 → 179.95); this reader serves cell centers (±89.975, ±179.975) with latitude ascending, like every other reader, after checking the axes against the grid’s HDF-EOS5 StructMetadata.0 corners.

  • Temporal resolution: Daily (using 16 days of accumulated observations)

  • Parameters: 3 RossThick-LiSparse (RTLS) kernel coefficients × 3 broadbands (shortwave, visible, near-infrared) = 9 output variables

BRDF kernel parameters#

RTLS decomposition: R = f_iso + f_vol * k_vol + f_geo * k_geo

fiso — isotropic (Lambertian) scattering weight fvol — volume scattering (Ross-Thick kernel) weight fgeo — geometric (Li-Sparse) scattering weight

These are dimensionless; values range from 0.0 to ~3.0 for fiso and ~1.0 for fvol/fgeo. Stored as int16; each field’s own _FillValue (32767), valid_range (0..32766), scale_factor (0.001) and add_offset (0) are applied.

Output variable naming: {band}_{param}

Band

HDF5 field suffix

shortwave

shortwave

vis

vis

nir

nir

Parameter

HDF5 field prefix

fiso

BRDF_Albedo_Parameter1

fvol

BRDF_Albedo_Parameter2

fgeo

BRDF_Albedo_Parameter3

References

Product page:

https://www.earthdata.nasa.gov/data/catalog/lpcloud-vj143c1-002

User guide:

https://lpdaac.usgs.gov/documents/194/VNP43_User_Guide_V2.pdf

Data access:

https://e4ftl01.cr.usgs.gov/VIIRS/VJ143C1.002/ (Earthdata login required)

File naming:

VJ143C1.A{YYYYDDD}.{version}.{YYYYDDDHHMMSS}.h5

Classes

VIIRSBRDFReader(file_paths)

Read VIIRS surface BRDF model parameters from a VJ143C1 HDF5 file.