Skip to main content

Description

The VCD19A3CMG Version 2 data product is a combined NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) and NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Vegetation Index and Snow Products Level 3 product produced daily in a 0.05 degree (5,600 meters at the equator) Climate Modeling Grid (CMG). The VCD9A3CMG product is corrected for atmospheric gases and aerosols using a Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm that is based on a time series analysis and a combination of pixel- and image-based processing.

The VCD19A3CMG Vegetation Index and Snow product contains variables for NDVI (Normalized Difference Vegetation Index), NDVI normalized to a fixed geometry, gap_filled daily NDVI for forward and backward scattering, daily Enhanced Vegetation Index (EVI) normalized to a fixed geometry, snow fraction, and snow grain size. A low-resolution browse image is also included.

Known Issues

• MAIAC Lookup Tables (LUTs) are built assuming pseudo-spherical correction in single scattering which has a reduced accuracy for high sun/view zenith angles. A reduced MAIAC performance is expected at solar zenith angles > 78°.

• MAIAC may be missing bright salt pans in several world deserts. In such cases, it may generate a persistent high Aerosol Optical Depth (AOD) resulting in missing surface retrievals.

• Because of inherent uncertainties of gridding on the coastline, the area of 1-3 pixels from the coastline may contain frequent artifacts in cloud mask (usually over-detection), AOD (higher values) and surface BRF. Users should exercise caution near the coastline as represented by the AOD QA bit 1010 (See Table 5.4 of the User Guide bits 8-11, 1010 -- AOD within +-2 km from the coastline is replaced by nearby AOD).

• Atmospheric Correction (AC) over detected snow: as MAIAC does not retrieve AOD over snow, it assumes a low climatology AOD=0.05 globally and 0.02 at high elevations (H>4.2 km). Over north-central China, which is often heavily polluted and low AOD assumption can lead to a significant bias, we use AOD averaged over mesoscale area of 150 km using reliable AOD retrievals over snow-free pixels. Such approach does improve quality of AC as compared to low-AOD assumption as judged by the reduced boundaries and color artifacts, but it does not account for the aerosol variability inside 150 km area.

• Ice mask is currently unreliable

Version Description

Combined NOAA-20 (JPSS-1) and Suomi NPP (S-NPP) VIIRS data products, designated as "VCD", were introduced in VIIRS Version 2.

Product Summary

Platforms
Suomi-NPP ,
NOAA-20
Instruments
VIIRS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
5600 Meters x 5600 Meters
Spatial Reference System(s)
VIIRS Climate Modeling Grid (CMG)
Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2012-01-17 to Present
Temporal Resolution
1 Day
Data Partner
Land Processes Distributed Active Archive Center (LP DAAC) ,
Land Science Investigator-led Processing System, Terrestrial Information Systems Laboratory, Earth Sciences Division, Sciences and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/LandSIPS)
Concept ID
C3588456969-LPCLOUD
Data State
ACTIVE
Number of Files/Granules
5067
Processing Level
3
Published
Updated
Science Keywords
Evapotranspiration ,
Evaporation ,
Latent Heat Flux

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

Lyapustin, A. (2026). VIIRS/NPP+JPSS Combined Vegetation Index and Snow Products from MAIAC Daily L3 Global at 0.05Deg CMG V002 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/VIIRS/VCD19A3CMG.002 Date Accessed: 2026-04-16

File Naming Convention

VCD19A3CMG.A2021240.002.2025188150851.h5

The file name begins with the Product Short Name (VCD19A3CMG) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2021240), the Version of the data collection (002), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2025188150851), and the Data Format (h5).

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
EVI_n Daily EVI normalized to SZA=45. and nadir view N/A int16 -28672 0 to 10000 0.0001 N/A
NDVI Gap-filled Daily Normalized Difference Vegetation Index at surface, normalized to nadir view and sun angle at 1:30pm local time N/A int16 -28672 0 to 10000 0.001 N/A
NDVI_Backward Gap-filled Daily NDVI, backward scattering direction N/A int16 -28672 0 to 10000 0.0001 N/A
NDVI_Forward Gap-filled Daily NDVI, forward scattering direction N/A int16 -28672 0 to 10000 0.0001 N/A
NDVI_n Daily Normalized Difference Vegetation Index at surface, normalized to nadir view and SZA=45. N/A int16 -28672 0 to 10000 0.001 N/A
Snow_Fraction Snow fraction (0-1.6) N/A int16 -28672 0 to 16000 0.0001 N/A
Snow_Grain_Size Snow grain diameter (mm) mm int16 -28672 0 to 30000 0.001 N/A
You're viewing 7 of 7