ASTER L2 Surface Kinetic Temperature V004

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Kinetic Temperature (AST_08) V004 product delivers surface kinetic temperature data derived from the five Thermal Infrared (TIR) bands (Bands 10–14), collected during both daytime and nighttime observations. The AST_08 product has a spatial resolution of 90 meters (m) for the TIR bands. This Level 2 (L2) product is produced using the Temperature/Emissivity Separation (TES) algorithm, which processes atmospherically corrected ASTER surface radiance (TIR) data to estimate emissivity and compute temperature. In Version 4, atmospheric correction has been significantly improved by integrating Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) data, enhancing the accuracy of temperature retrievals.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.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.