ASTER L2 Surface Radiance VNIR and Crosstalk Corrected SWIR V004

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Radiance VNIR and Crosstalk Corrected SWIR (AST_09XT) contains atmospherically corrected data for the Visible and Near Infrared (VNIR) and Shortwave Infrared (SWIR) sensors. The AST_09XT product has a spatial resolution of 15 meters (m) for the VNIR bands and 30 m for the SWIR bands. Both the VNIR and the SWIR data are atmospherically corrected using the corresponding bands from an ASTER [Level 1B](https://doi.org/10.5067/ASTER/AST_L1B.004) image.Known Issues* Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the UTM zone defined in the file metadata.* SWIR data acquired after April 2008 may exhibit anomalous saturation and striping. Users should consult the ASTER SWIR User Advisory for additional details.Improvements/Changes from Previous Versions* SWIR Crosstalk Correction: Applies a correction to reduce stray light effects in the SWIR bands, enhancing data quality by minimizing artifacts. Enhanced Atmospheric Correction: Version 4 uses Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) data as the primary source for atmospheric parameters (ozone, water vapor, pressure, and temperature), improving the precision of emissivity calculations. Fallback Mechanisms: When MERRA-2 data are unavailable, the product employs Global Data Assimilation System (GDAS) data as a backup, with climatology data serving as a final fallback to ensure continuous processing. Radiometric Calibration Update: Version 4 applies Radiometric Calibration Coefficient Version 5 (RCC V5) to improve the radiometric accuracy of the raw DNs, based on research by [Tsuchida and others (2020)](https://doi.org/10.3390/rs12030427), published in Remote Sensing.