Atmospheric Ancillary Input Changes to ASTER Level 2 Product Generation Executables

[LP DAAC - jwilson]

As of December 18, 2024, ASTER Product Generation Executables (PGE) Version 3.4-3_9 has implemented a new ancillary input in the atmospheric correction of ASTER Level (L2) data products.

The Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) is a global atmospheric reanalysis that combines remote sensing observations and interactions with the climate system. It will be one of the primary ozone and water vapor, pressure, and temperature inputs for all L2 PGEs. MERRA-2 will provide a finer geographic resolution grid since it is a 3-dimensional, 3-hour data collection with a 50-km (latitudinal direction) spatial resolution.

The fallback options for the new 3.4-3_9 L2 PGEs when using the MERRA2 input will apply equally to both the Ozone and Water Vapor, Pressure and Temperature inputs (MERRA-2, GDAS, and CLIMATOLOGY).

The fallback options for the new 3.4-3_9 L2 PGEs without the MERRA2 input will apply separately to the Ozone (OZ_DLY, AURAOMI, TOAST, EPTOMS, GDAS, and CLIMATOLOGY) and Water Vapor, Pressure and Temperature (MOD07_L2, GDAS, and CLIMATOLOGY) inputs.

Users should be aware that the temporal range for MERRA-2 covers 1980 to present; however, there is latency of ~3 weeks after the end of a month. Hence, NCEP/GDAS > Climatology fallback sequence will be applied for on-demand requests that fall outside of MERRA-2’s temporal range or if the data is not science grade.

The following list of ASTER Level 2 on-demand products are impacted:

ASTER L2 Surface Emissivity (AST_05)
ASTER L2 Surface Reflectance VNIR and SWIR (AST_07)
ASTER L2 Surface Reflectance SWIR Crosstalk-Corrected (AST_07XT)
ASTER L2 Surface Kinetic Temperature (AST_08)
ASTER L2 Surface Radiance VNIR and SWIR (AST_09)
ASTER L2 Surface Radiance SWIR Crosstalk-Corrected (AST_09XT)
ASTER L2 Surface Radiance TIR (AST_09T)
Due to ASTER's safe mode, no new data has been acquired since November 28th. Additional information can be found here.

Contact LP DAAC User Services with any questions or concerns.
https://lpdaac.usgs.gov/news/atmospheric-ancillary-input-changes-to-aster-level-2-product-generation-executables/