{"@type": "dcat:Dataset", "accessLevel": "public", "bureauCode": ["026:00"], "contactPoint": {"@type": "vcard:Contact", "fn": "Earthdata Forum", "hasEmail": "mailto:earthdata-support@nasa.gov"}, "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.\n\nThe 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.\n\nKnown Issues\n\n* 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\u00b0. \n* 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. \n* 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).\n* 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. \n* Ice mask is currently unreliable", "distribution": [{"@type": "dcat:Distribution", "conformsTo": "http://www.isotc211.org/2005/gmi", "description": "The metadata's original source.", "downloadURL": "https://cmr.earthdata.nasa.gov/search/concepts/C3588456969-LPCLOUD.iso19115", "format": "ISO", "mediaType": "text/xml", "title": "Original Metadata"}, {"@type": "dcat:Distribution", "downloadURL": "https://doi.org/10.5067/VIIRS/VCD19A3CMG.002", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://landweb.modaps.eosdis.nasa.gov", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://lpdaac.usgs.gov/documents/2268/VNP19_User_Guide_V1.pdf", "format": "PDF", "mediaType": "application/pdf"}, {"@type": "dcat:Distribution", "downloadURL": "https://search.earthdata.nasa.gov/search/granules?p=C3588456969-LPCLOUD", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://viirsland.gsfc.nasa.gov/Val_overview.html", "format": "HTML", "mediaType": "text/html"}, {"@type": "dcat:Distribution", "downloadURL": "https://www.earthdata.nasa.gov/centers/lp-daac", "format": "BIN", "mediaType": "application/octet-stream"}], "identifier": "10.5067/VIIRS/VCD19A3CMG.002", "keyword": ["earth-science-cryospheric-indicators-climate-indicators-snow-cover", "earth-science-glaciers-ice-sheets-cryosphere-firn", "earth-science-surface-radiative-properties-land-surface-reflectance", "earth-science-vegetation-biosphere-vegetation-index"], "license": "https://www.usa.gov/government-works", "modified": "2026-06-23", "programCode": ["026:000"], "publisher": {"@type": "org:Organization", "name": "LP DAAC;NASA/GSFC/SED/ESD/TISL/LandSIPS"}, "spatial": "[\"CARTESIAN\", [{\"NorthBoundingCoordinate\": 90, \"WestBoundingCoordinate\": -180, \"EastBoundingCoordinate\": 180, \"SouthBoundingCoordinate\": -90}]]", "temporal": "2012-01-19/2026-06-15", "theme": ["Earth Science"], "title": "VIIRS/NPP+JPSS Combined\u00a0Vegetation Index\u00a0and Snow\u00a0Products\u00a0from MAIAC Daily L3 Global at\u00a00.05Deg CMG V002"}