MCD19A2 v006

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

PI: Alexei Lyapustin

The MCD19A2 Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the MCD19A2 Version 6.1 data product.


The MCD19A2 Version 6 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) gridded Level 2 product produced daily at 1 kilometer (km) pixel resolution. The MCD19A2 product provides the atmospheric properties and view geometry used to calculate the MAIAC Land Surface Bidirectional Reflectance Factor (BRF) or surface reflectance, MCD19A1 product.

The MCD19A2 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, fine mode fraction over water, column water vapor over land and clouds (in cm), smoke injection height (m above ground), AOD QA, AOD model at 1km, cosine of solar zenith angle, cosine of view zenith angle, relative azimuth angle, scattering angle, and glint angle at 5km. 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.

Each SDS layer within each MCD19A2 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.

read more


Improvements/Changes from Previous Versions

No previous versions.

Product Maturity

Validation at stage 1 has been achieved for the MODIS MAIAC products. Further details regarding MODIS land product validation for the MCD19 data products are available from the MODIS Land Team Validation site.

Collection and Granule


Characteristic Description
CollectionCombined MODIS
File Size~6.82 MB
Temporal ResolutionDaily
Temporal Extent2000-02-01 to 2023-02-17
Spatial ExtentGlobal
Coordinate SystemSinusoidal
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km


Characteristic Description
Number of Science Dataset (SDS) Layers13
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers / Variables

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Optical_Depth_047 Blue band (0.47 μm) aerosol optical depth over land N/A 16-bit signed integer -28672 N/A -100 to 5000 0.001
Optical_Depth_055 Green band (0.55 μm) aerosol optical depth over land N/A 16-bit signed integer -28672 N/A -100 to 5000 0.001
AOD_Uncertainty AOD uncertainty based on blue-band surface brightness (reflectance) N/A 16-bit signed integer -28672 N/A -100 to 30000 0.0001
FineModeFraction Fine mode fraction for ocean N/A 16-bit signed integer -28672 N/A 0 to 10000 0.0001
Column_WV Column Water Vapor (cm) over land cm 16-bit signed integer -28672 N/A 0 to 30000 0.001
Injection_Height Smoke injection height (m above ground) Meters 32-bit floating point -99999 N/A 0 to 10000 N/A
AOD_QA AOD QA N/A 16-bit unsigned integer 0 N/A 1 to 65535 N/A
AOD_MODEL AOD model used in retrieval N/A 8-bit unsigned integer 255 N/A 0 to 100 N/A
cosSZA Cosine of Solar zenith angle (5 km) N/A 16-bit signed integer -28672 N/A 0 to 10000 0.0001
cosVZA Cosine View zenith angle (5 km) N/A 16-bit signed integer -28672 N/A 0 to 10000 0.0001
RelAZ Relative azimuth angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01
Scattering_Angle Scattering Angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01
Glint_Angle Glint Angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01

The MCD19 SDS layers are three dimensional. The total number of bands in each file is contingent upon the number of orbit overpasses (1-2 at the equator and up to 30 in Polar Regions). For example, a file with an orbit number of five will contain five bands for each SDS layer (i.e. FineModeFraction will be recorded in 5 separate instances). Note that at high latitudes, only the first 16 orbits with the largest coverage are selected for processing per day in order to limit the file size.

Orbit information is stored in the Orbit_amount and Orbit_time_stamp attributes in the HDF file. The global metadata attributes of MODIS data products can be viewed in software such as HDFView and Panoply.

Product Quality

Quality assurance information should be considered when determining the usability of data for a particular science application. The ArcGIS MODIS-VIIRS Python Toolbox contains tools capable of decoding quality data layers while producing thematic quality raster files for each quality attribute.

The QC layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the QC layers.

Product quality information is described on pages 9 and 13 of the User Guide.

Known Issues

  • The longname in the internal metadata is provided incorrectly. The correct longname is "MODIS/Terra and Aqua MAIAC Land Aerosol Optical Depth Daily L2G 1 km SIN Grid."
  • Additional known issues are described on page 14 of the User Guide.

About the image

Combined MODIS Optical Depth 047 data from the MCD19A2 product over part of west Africa, June 3, 2018.

View full-size image


User Guide
Algorithm Theoretical Basis Document (ATBD)
File Specification

Using the Data

Access Data


DOI: 10.5067/MODIS/MCD19A2.006