MCD18A2 v006

MODIS/Terra+Aqua Photosynthetically Active Radiation Daily 3-Hour L3 Global 5 km SIN Grid


PI: Dongdong Wang

Description

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.

Characteristics

Product Maturity

MODIS radiation products from 2001 through 2008 are early release data validated to Beta maturity level. Data from 2018 to present have undergone additional processing that fixed various programming errors that negatively affected product accuracy and are considered to be validated to Provisional maturity status.

Collection and Granule

Collection

Characteristic Description
CollectionCombined MODIS
DOI10.5067/MODIS/MCD18A2.006
File Size~5 MB
Temporal ResolutionDaily
Temporal Extent2001-01-01 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
DatumN/A
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers12
Columns/Rows240 x 240
Pixel Size5600 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor Additional Offset
PAR Instantaneous total PAR at MODIS overpass W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
Direct Instantaneous direct PAR at MODIS overpass W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
Diffuse Instantaneous diffuse PAR at MODIS overpass W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_0000_PAR Total PAR at GMT 00:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_0300_PAR Total PAR at GMT 03:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_0600_PAR Total PAR at GMT 06:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_0900_PAR Total PAR at GMT 09:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_1200_PAR Total PAR at GMT 12:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_1500_PAR Total PAR at GMT 15:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_1800_PAR Total PAR at GMT 18:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
GMT_2100_PAR Total PAR at GMT 21:00 W/m² 32-bit floating point -1 N/A 0 to 700 N/A N/A
ViewZenithAngle View Zenith Angle of each MODIS overpass Degree 32-bit floating point -1 N/A 0 to 90 N/A N/A

See Table 2 in the User Guide for additional information on band dimensions.

Product Quality

For information about MCD18A2 product quality please refer to the MODIS Product Quality Documentation.

Known Issues

Known issues for MCD18A2 are available on the MODIS Land Quality Assessment website.

Documentation

Using the Data

Tools

Citation

DOI: 10.5067/MODIS/MCD18A2.006

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