MODIS/Terra+Aqua Land Aerosol Optical Depth Daily L2G Global 1km SIN Grid V061

The MCD19A2CMG Version 6.1 data product is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Multi-Angle Implementation of Atmospheric Correction (MAIAC) 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 MCD19A2CMG product provides the atmospheric properties and view geometry used to calculate the MAIAC Surface Reflectance data products (MCD19A1CMGL and MCD19A1CMGO). The MCD19A2CMG AOD data product contains the following Science Dataset (SDS) layers: blue band AOD at 0.47 µm, green band AOD at 0.55 µm, AOD uncertainty, column water vapor for Terra, column water vapor for Aqua, average cloud fraction, available AOD, satellite overpass times, line and sample number, offset, and number of AOD records. A low-resolution browse image is also included showing AOD of the blue band at 0.47 µm created using a composite of all available orbits. 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 MCD19A1 Version 6.1 data product is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Land Surface Bidirectional Reflectance Factor (BRF) gridded Level 2 product produced daily at 500 meter (m) and 1 kilometer (km) pixel resolutions. The MCD19A1 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 MODIS 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. The MCD19A1 MAIAC Surface Reflectance data product includes 31 Science Dataset (SDS) layers: surface reflectance for bands 1-12, BRF uncertainty for bands 1-2, Quality Assessment (QA) bits at 1 km, surface reflectance for bands 1-7 at 500 m, cosine of solar zenith angle, cosine of view zenith angle, relative azimuth angle, scattering angle, solar azimuth angle, view azimuth angle, glint angle, RossThick/Li-Sparse (RTLS) volumetric kernel, and RTLS geometric kernel at 5 km. A low-resolution browse image is also included showing surface reflectance band combination 1, 4, 3 created using a composite of all available orbits. Each SDS layer within each MCD19A1 Hierarchical Data Format 4 (HDF4) file contains a third dimension that represents the number of orbit overpasses. This factor could affect the total number of bands for each SDS layer. 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 VJ219A2 Version 2 data product is a NOAA-21 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Aerosol Optical Depth (AOD) gridded Level 2 product produced daily at 750 meter (m) pixel resolution using the Rotated Sinusoidal (RSIN) projection. The VJ219A2 product provides the atmospheric properties and view geometry used to calculate the Multi-Angle Implementation of Atmospheric Correction (MAIAC) Land Surface Bidirectional Reflectance Factor (BRF) or surface reflectance, VJ219A1 product. Provided in the VJ219A2 product are layers for AOD, AOD uncertainty and QA, injection height of smoke plume, AOD outside of glint area, fine mode fraction, and cosines of solar and view zenith angles, relative azimuth, scattering angle, glint angle, and Angstrom Exponent over the ocean. 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 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 MCD19A1CMGO 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 8-12) product produced daily in a 0.05 degree (5,600 meters at the equator) Climate Modeling Grid (CMG). The MCD19A1CMGO 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 MCD19A1CMGO MAIAC Surface Reflectance product for ocean bands includes 19 Science Dataset (SDS) layers: BRF for bands 8-12, BRF normalized to a fixed geometry for bands 8-12, NBAR for bands 8-12, 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 VJ119A2 Version 2 data product is a NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Aerosol Optical Depth (AOD) gridded Level 2 product produced daily at 750 meter (m) pixel resolution using the Rotated Sinusoidal (RSIN) projection. The VJ119A2 product provides the atmospheric properties and view geometry used to calculate the Multi-Angle Implementation of Atmospheric Correction (MAIAC) Land Surface Bidirectional Reflectance Factor (BRF) or surface reflectance, VJ119A1 product. Provided in the VJ119A2 product are layers for AOD, AOD uncertainty and QA, injection height of smoke plume, AOD outside of glint area, fine mode fraction, and cosines of solar and view zenith angles, relative azimuth, scattering angle, glint angle, and Angstrom Exponent over the ocean. Known Issues * The spatial resolution and projection of this product are listed incorrectly in the VJ119A2 long name. VJ119A2 uses the RSIN projection and is at 750 m resolution. The long name should read “VIIRS/JPSS1 Land Aerosol Optical Depth Daily L2G Global 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.