VIIRS/NPP+JPSS Combined Surface Reflectance from MAIAC Daily L3 Global at 0.05Deg CMG V002

The VCD19A2CMG 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) Land Aerosol Optical Depth (AOD) and Water Vapor Level 3 product produced daily in a 0.05 degree (5,600 meters at the equator) Climate Modeling Grid (CMG). The VCD9A2CMG 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 VCD19A2CMG AOD data product contains the variables for blue band AOD at 0.47 µm, green band AOD at 0.55 µm, AOD uncertainty, average cloud fraction, available AOD, satellite overpass times, line and sample number, offset, and number of AOD records. 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.

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. 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

The VCD19A3 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) Land Surface Bidirectional Reflectance Factor (BRF) gridded Level 3 product produced daily at 750 meter (m) pixel resolution using the Rotated Sinusoidal (RSIN) projection. The VCD9A3 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 VIIRS MAIAC Land Surface BRF products provide an estimate of the surface spectral reflectance as it would be measured at ground-level in the absence of atmospheric scattering or absorption. VCD19A3 product provides three coefficients (weights) of the Ross-Thick 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 variable. Over snow-free land, MAIAC also reports gap-filled Normalized Difference Vegetation Index (NDVI) at 375 m and 750 m resolution. The VCD19A3 BRDF Model Parameters product contains the following Science Dataset (SDS) variables: 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, and five separate variables for the number of days since last update to current day. 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. Effective as of April 14, 2026, the processing of selected overlapping VIIRS MAIAC tiles within the forward stream has been discontinued to eliminate redundant data. A complete list of the excluded tiles can be found at VIIRS MAIAC Reduced Tiles.

The VJ119A1 Version 2 data product is a NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Bidirectional Reflectance Factor (BRF) gridded Level 2 product produced daily at 375 meter (m) and 750 m pixel resolutions using the Rotated Sinusoidal (RSIN) projection. The VJ119A1 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 VIIRS MAIAC Land Surface BRF products provide an estimate of the surface spectral reflectance as it would be measured at ground-level in the absence of atmospheric scattering or absorption. Provided in the VJ119A1 product are variables for surface reflectance, cosines of solar and view zenith angles, relative azimuth, sun azimuth (SAZ), sensor view azimuth (VAZ), scattering angle and glint angle. Volumetric (Fv) and geometric-optics (Fg) kernels of the Ross-Thick Li-Sparce (RTLS) model for the observation geometry are also included. The 750 m surface reflectance variables are produced in cloud-free conditions from bands M1-M5, M7, M8, M10, and M11, whereas the 375 m variables are produced from bands I1-I3. Known Issues * The spatial resolution and projection of this product are listed incorrectly in the VJ119A1 long name. VJ119A1 uses the RSIN projection and is at 375 m and 750 m resolution. The long name should read “VIIRS/JPSS1 Land Surface BRF Daily L2G Global 375m and 750m RSIN Grid V002”. This will be rectified in future versions. * 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. * Effective as of April 14, 2026, the processing of selected overlapping VIIRS MAIAC tiles within the forward stream has been discontinued to eliminate redundant data. A complete list of the excluded tiles can be found at VIIRS MAIAC Reduced Tiles.

The MCD19A1CMGL Version 6.1 data product is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Multi-Angle Implementation of Atmospheric Correction (MAIAC) Surface Reflectance Level 3 (Bands 1-7) product produced daily in a 0.05 degree (5,600 meters at the equator) Climate Modeling Grid (CMG). The MCD19A1CMGL product is corrected for atmospheric gases and aerosols using a new MAIAC algorithm that is based on a time series analysis and a combination of pixel- and image-based processing. The MODIS MAIAC products provide an estimate of the surface spectral reflectance, also referred to as Bidirectional Reflectance Factor (BRF), as it would be measured at ground-level in the absence of atmospheric scattering or absorption. The Surface Reflectance dataset includes BRF, BRF normalized to a fixed geometry of solar zenith angle at 45° and nadir view, and Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) normalized to the nadir view and local sun angle at 1:30 pm. The MCD19A1CMGL MAIAC Surface Reflectance product for land bands includes 25 Science Dataset (SDS) layers: BRF for bands 1-7, BRF normalized to a fixed geometry for bands 1-7, NBAR for bands 1-7, Quality Assessment (QA) bits, cosine of solar zenith angle, cosine of view zenith angle, and relative azimuth angle. A low-resolution browse is also included. Known Issues * Known issues are described in Section 6 of the User Guide. * For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

The VJ219A1 Version 2 data product is a NOAA-21 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Bidirectional Reflectance Factor (BRF) gridded Level 2 product produced daily at 375 meter (m) and 750 m pixel resolutions using the Rotated Sinusoidal (RSIN) projection. The VJ219A1 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 VIIRS MAIAC Land Surface BRF products provide an estimate of the surface spectral reflectance as it would be measured at ground-level in the absence of atmospheric scattering or absorption. Provided in the VJ219A1 product are variables for surface reflectance, cosines of solar and view zenith angles, relative azimuth, sun azimuth (SAZ), sensor view azimuth (VAZ), scattering angle and glint angle. Volumetric (Fv) and geometric-optics (Fg) kernels of the Ross-Thick Li-Sparce (RTLS) model for the observation geometry are also included. The 750 m surface reflectance variables are produced in cloud-free conditions from bands M1-M5, M7, M8, M10, and M11, whereas the 375 m variables are produced from bands I1-I3. Known Issues * The spatial resolution and projection of this product are listed incorrectly in the VJ219A1 long name. VJ219A1 uses the RSIN projection and is at 375 m and 750 m resolution. References to 350 m are in error. The long name should read “VIIRS/JPSS2 Land Surface BRF Daily L2G Global 375m and 750m RSIN Grid V002”. This will be rectified in future versions. * 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. * Effective as of April 14, 2026, the processing of selected overlapping VIIRS MAIAC tiles within the forward stream has been discontinued to eliminate redundant data. A complete list of the excluded tiles can be found at VIIRS MAIAC Reduced Tiles.