Combined MODIS NDVI data from the MCD19A3D product over part of west Africa, January 9, 2001.View full-size image
The MCD19A3D Version 6.1 data product is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Bidirectional Reflectance Distribution Function (BRDF) Model Parameters gridded Level 3 product. Output daily at 1 kilometer (km) resolution, the Multi-angle Implementation of Atmospheric Correction (MAIAC) MCD19A3D product provides three coefficients (weights) of the RossThick/Li-Sparse (RTLS) BRDF model that can be used to describe the anisotropy of each pixel. The retrievals represent cloud-free and low aerosol conditions.
When snow is detected, gap-filled snow grain size and sub-pixel snow fraction are computed. The gap-filling process retains the parameter in MAIAC’s memory for each grid cell until updated with the latest cloud-free observation. The number of days since the last update is provided in a separate layer.
Over snow-free land, MAIAC also reports gap-filled Normalized Difference Vegetation Index (NDVI) at 1 km resolution and gap-filled Nadir BRDF-Adjusted Reflectance (NBAR) at 250 meter (m) resolution in the red and near-infrared (NIR) bands.
The MCD19A3D BRDF Model Parameters product contains the following Science Dataset (SDS) layers: RTLS isotropic kernel parameter (Kiso) for bands 1-8, the RTLS volumetric kernel parameter (Kvol) for bands 1-8, RTLS geometric kernel parameter (Kgeo) for bands 1-8, three snow parameters, NDVI, NBAR, and three separate layers for the number of days since last update to current day.
|File Size||~35 MB|
|Temporal Extent||2000-02-24 to Present|
|Geographic Dimensions||1200 km x 1200 km|
|Number of Science Dataset (SDS) Layers||11|
|Columns/Rows||1200 x 1200|
|Pixel Size||1000 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|Kiso¹||RTLS isotropic kernel parameter for bands 1-8||N/A||16-bit signed integer||-32767||N/A||-32766 to 32767||0.0001|
|Kvol¹||RTLS volumetric kernel parameter for bands 1-8||N/A||16-bit signed integer||-32767||N/A||-32766 to 32767||0.0001|
|Kgeo¹||RTLS geometric kernel parameter for bands 1-8||N/A||16-bit signed integer||-32767||N/A||-32766 to 32767||0.0001|
|Snow_Fraction||Snow Fraction in 1km pixel||N/A||16-bit signed integer||-28672||N/A||0 to16000||0.0001|
|Snow_Grain_Size||Snow Grain Diameter (mm)||mm||16-bit signed integer||-28672||N/A||0 to 30000||0.0001|
|Snow_Fit||Snow Reflectance RMSE in Band 1, 5 and 7||N/A||16-bit signed integer||-28672||N/A||0 to 30000||0.0001|
|Snow_UpdateDay||Number of days from last update to current day for snow fraction and snow grain size||N/A||8-bit unsigned integer||255||N/A||0 to 254||N/A|
|NDVI1km||Daily Normalized Difference Vegetation Index, gap-filled||N/A||16-bit signed integer||-28672||N/A||0 to 10000||0.0001|
|UpdateDay||Number of days from last update to current day for Kiso, Kvol and Kgeo||N/A||8-bit unsigned integer||255||N/A||0 to 254||N/A|
|NDVI_NBAR_UpdateDay||Number of days from last update to current day for NDVI and NBAR||N/A||8-bit unsigned integer||255||N/A||0 to 254||N/A|
|NBAR_250m||Nadir BRDF-Adjusted Reflectance, Band 1 and 2||N/A||16-bit signed integer||-28672||N/A||-100 to 16000||0.0001|
¹Each SDS layer contains information for bands 1-8.
Caveats are noted in Section 6 of the User Guide.
Known issues are described in Section 6 of the User Guide.
An artifact was discovered in the NDVI1km and NBAR_250m layers over the southern polar region. The affected region shows false retrieval of data during the summer months. The artifacts occurred over permanently snow-covered areas where no meaningful NDVI retrieval is expected. A software fix was implemented for forward processing in June 2023. Existing data products will not be reprocessed. Affected dates are listed on the Land Data Operational Products Evaluation Quality Assessment note.