MCD18A2: Daily and 3-Hour Photosynthetically Active Radiation from MODIS Satellites

MCD18A2 Version 6 is a decommissioned NASA MODIS data product providing daily and 3-hour estimates of Photosynthetically Active Radiation (PAR) at a 5-kilometer resolution. The product combines data from the Terra and Aqua satellites to model incident solar radiation in the 400-700 nanometer spectrum, which is used in land-surface models. Users are directed to use the newer MCD18A2 Version 6.2 product.

Use Cases

• Modeling vegetation productivity and carbon cycles based on incident solar radiation in the visible spectrum.
• Assessing surface energy budgets for climate models using 3-hourly PAR estimates.
• Calibrating or validating other remote sensing products using the derived surface reflectance and PAR layers.
• Studying the impact of aerosols and clouds on light availability for photosynthesis using the algorithm's look-up table approach.

Strengths

• Provides data at a 5-kilometer pixel resolution, offering moderate spatial detail for global analysis.
• Includes both daily and 3-hourly temporal estimates of PAR, capturing diurnal cycles.
• Algorithm uses multi-temporal MODIS signatures and considers varying aerosol/cloud loadings and geometry.

Limitations

• This specific version (V006) was decommissioned in October 2022, indicating it is not the current operational product.
• Column-level documentation is absent; field semantics must be inferred after download.
• Known issues exist, requiring users to consult external quality assessment websites for complete information.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Data is derived from combined Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites using a prototyping algorithm.

Time Range

Daily production.

Freshness

Last updated 2026-03-12 23:36:56.987737; freshness should be verified as the product version is decommissioned.

Geography

Global coverage on a sinusoidal grid.