Combined MODIS Aerosol Optical Depth 047 data from the MCD19A2CMG product across the globe, September 26, 2009.View full-size image
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.
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|File Size||~50 MB|
|Temporal Extent||2000-02-24 to Present|
|Coordinate System||Geographic Latitude and Longitude|
|Number of Science Dataset (SDS) Layers||12|
|Columns/Rows||7200 x 3600|
|Pixel Size||5600 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|AOD_055||Daily averaged AOD for 550nm band||N/A||16-bit signed integer||-28672||N/A||0 to 6000||0.001|
|AOD_047||Daily averaged AOD for 470nm band||N/A||16-bit signed integer||-28672||N/A||0 to 6000||0.001|
|Sigma_AOD_055||Standard deviation/Uncertainty of daily AOD for 550nm band||N/A||16-bit signed integer||-28672||N/A||0 to 30000||0.0001|
|ColumnWaterVapor _Terra||Daily average of column water vapor for Terra in cm||cm||16-bit signed integer||-28672||N/A||0 to 30000||0.001|
|ColumnWaterVapor _Aqua||Daily average of column water vapor for Aqua in cm||cm||16-bit signed integer||-28672||N/A||0 to 30000||0.001|
|CloudFraction||Daily average cloud fraction||N/A||16-bit signed integer||-28672||N/A||0 to 10000||0.0001|
|Compact_AOD_055||AOD record compacted into 1-D array, for 550nm band||N/A||16-bit signed integer||N/A||N/A||0 to 6000||0.001|
|OverpassTime||Satellite overpass time incorresponding AOD record,minutes since 00:00 of the given day||N/A||16-bit signed integer||N/A||N/A||0 to 1440||N/A|
|Line||X coordinate of compacted AOD record||N/A||16-bit signed integer||N/A||N/A||0 to 3599||N/A|
|Sample||Y coordinate of compacted AOD record||N/A||16-bit signed integer||N/A||N/A||0 to 7199||N/A|
|Offset_AOD_055||Offset in compacted AOD record||N/A||32-bit signed integer||N/A||N/A||N/A||N/A|
|nAOD||Number of AOD in compacted AOD record||N/A||16-bit signed integer||N/A||N/A||0 to 100||N/A|
The CMG AOD file stores the daily average AOD (at 0.47 and 0.55µm) as well as AOD from all overpass orbits for a given day. Since the individual orbit data are sparse due to clouds (snow), the orbital data are stored in a compact way, similar to the MOD09 product. The compact format is described in more detail in Section 10 in the User Guide.
Product quality information is described in Section 5.8 in the User Guide.
Known issues are described in Section 6 of the User Guide.