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Description

MCD18A2 Version 6 was decommissioned on October 28, 2022. Users are encouraged to use the MCD18A2 Version 6.2 data product.

The MCD18A2 Version 6 is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Photosynthetically Active Radiation (PAR) gridded Level 3 product produced daily at 5 kilometer pixel resolution with estimates of PAR every 3 hours. PAR is incident solar radiation in the visible spectrum (400-700 nanometers) and is an important variable in land-surface models that address a variety of scientific and application issues. The MCD18 products are based on a prototyping algorithm that uses multi-temporal signatures of MODIS data to derive surface reflectance and then calculate incident PAR using the look-up table (LUT) approach. The LUTs consider different types of loadings of aerosols and clouds at a variety of illumination/viewing geometry. Global PAR products are generated from MODIS and geostationary satellite data. Additional details regarding the methodology used to create the data are available in the Algorithm Theoretical Basis Document (ATBD).

Provided in the MOD18A2 product are layers for instantaneous PAR array for each individual MODIS overpass and 3-hour PAR array along with a View Zenith Angle layer.

Known Issues

Product Summary

Platforms
Aqua,
Terra
Instruments
MODIS
Spatial Extent
N: 90 S: -90 E: 180 W: -180
Spatial Resolution
5600 Meters x 5600 Meters
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2001-01-01 to 2022-09-30
Temporal Resolution
3 Hour
Data Partner
Land Processes Distributed Active Archive Center (LP DAAC)
MODIS Adaptive Processing System, Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/MODAPS)
Concept ID
c2763289456-lpcloud
Data State
DEPRECATED
Processing Level
3
Published
Updated

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Wang, D. (2017). MODIS/Terra+Aqua Photosynthetically Active Radiation Daily/3-Hour L3 Global 5km SIN Grid V006 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/MODIS/MCD18A2.006 Date Accessed: 2025-07-30

Data Center Citation

Dongdong Wang. 2017. MODIS/Terra+Aqua Photosynthetically Active Radiation Daily/3-Hour L3 Global 5km SIN Grid V006. Sioux Falls, South Dakota, USA: NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/MODIS/MCD18A2.006.

Documents

ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD) The ATBD provides physical theory and mathematical procedures for the calculations used to produce the data products.
GENERAL DOCUMENTATION The File Specification provides a description of the product file including Scientific Data Sets and their attributes.
PRODUCT QUALITY ASSESSMENT The LDOPE Land Product Quality Assessment website provides known issues, maneuvers, and product quality of the land products.
USER'S GUIDE The technical information in the User's Guide enables users to interpret and use the data products.

Learning Resources

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