MCD43D31 v006

MODIS/Terra and Aqua BRDF/Albedo QA BRDF Quality Daily L3 Global 30 ArcSec CMG


PI: Crystal Schaaf

Description

The MCD43D31 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) QA BRDF Quality dataset is produced daily using 16 days of Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data at 30 arc second (1,000 meter (m)) resolution. Data are temporally weighted to the ninth day which is reflected in the Julian date in the file name. This Climate Modeling Grid (CMG) product covers the entire globe for use in climate simulation models. MCD43D31 provides BRDF/Albedo quality information for the MCD43D products.

MCD43D31 consists of a BRDF quality layer representing the overall quality of each pixel along with an individual BRDF/Albedo quality layer for MODIS spectral bands 1 through 7.

Characteristics

Improvements/Changes from Previous Versions

  • Observations are weighted to estimate the BRDF/Albedo on the ninth day of the 16-day period.
  • MCD43 products use the snow status weighted to the ninth day instead of the majority snow/no-snow observations from the 16-day period.
  • Better quality at high latitudes from use of all available observations for the acquisition period. Collection 5 used only four observations per day.
  • The MCD43 products use L2G-lite surface reflectance as input.
  • When there are insufficient high quality reflectances, a database with archetypal BRDF parameters is used to supplement the observational data and perform a lower quality magnitude inversion. This database is continually updated with the latest full inversion retrieval for each pixel.
  • CMG Albedo is estimated using all the clear-sky observations within the 1,000 m grid for MCD43D as opposed to aggregating from the 500 m albedo.

Product Maturity

The MODIS BRDF/Albedo products have achieved stage 3 validation.

Collection and Granule

Collection

Characteristic Description
CollectionCombined MODIS
DOI10.5067/MODIS/MCD43D31.006
File Size~27 MB
Temporal ResolutionDaily
Temporal Extent2000-02-16 to Present
Spatial ExtentGlobal
Coordinate SystemGeographic Latitude and Longitude
DatumN/A
File FormatHDF-EOS
Geographic DimensionsGlobal

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers8
Columns/Rows43200 x 21600
Pixel Size~1000 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor Additional Offset
BRDF_Quality BRDF quality N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band1 BRDF/Albedo quality for MODIS band 1 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band2 BRDF/Albedo quality for MODIS band 2 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band3 BRDF/Albedo quality for MODIS band 3 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band4 BRDF/Albedo quality for MODIS band 4 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band BRDF/Albedo quality for MODIS band 5 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band6 BRDF/Albedo quality for MODIS band 6 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A
BRDF_Albedo_Band_Quality_Band7 BRDF/Albedo quality for MODIS band 7 N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A N/A

BRDF Quality description

Value Description
0 Processed, good quality, full BRDF inversions
1 Processed, magnitude BRDF inversions
255 Fill value

BRDF/Albedo Band Quality description

Value Description
0 Best quality, full inversion (Weight of Determination (WoDs), Root Mean Square Error (RMSE) majority good)
1 Good quality, full inversion (also including the cases that no clear sky observations over the day of interest or the Solar Zenith Angle is too large even WoDs, RMSE majority good)
2 Magnitude inversion (numobs >=7)
3 Magnitude inversion (numobs >=2 & <7)
255 Fill value

Product Quality

The quality layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the QC layers.

Known Issues

For complete information about MCD43D31 known issues refer to the MODIS Land Quality Assessment website.

Documentation

Using the Data

Tools

Citation

DOI: 10.5067/MODIS/MCD43D31.006

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