ASTER L2 Surface Emissivity 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. Acquisitions for AST_08 ended on January 16, 2026, at 05:10:45 UTC, when the ASTER TIR instrument was permanently turned off due to power limitations on the Terra spacecraft. More information is available in this NASA Science News Brief.  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.

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Radiance TIR (AST_09T) is generated using the five Thermal Infrared (TIR) bands (acquired either during the day or nighttime) between 8 and 12 µm spectral range. It provides surface-leaving radiance for the TIR bands at a spatial resolution of 90 meters, which includes both surface-emitted and surface-reflected components. It also provides the downwelling sky irradiance values (in W/m2/µm) for each of the TIR bands. This product is atmospherically corrected, and the surface-leaving radiance is of known accuracy and valid only for clear-sky scenes (cloud-free pixels). This atmospherically corrected product provides the input for generating two other higher level products: surface spectral emissivity and surface kinetic temperature. The algorithm to correct atmospheric effects involves two elements. First, it uses a radiative transfer model—the Moderate Resolution Transmittance Code (MODTRAN)—which can estimate the magnitude of atmospheric emission, absorption, and scattering. MODTRAN calculates atmospheric transmittance and radiance for frequencies from 0 to 50,000 cmˉ¹ at moderate spectral resolution. Second, it identifies and incorporates all the necessary atmospheric parameters applicable to the location and time for which the measurements require correction, including temperature, water vapor, elevation, ozone, and aerosols. Acquisitions for AST_09T ended on January 16, 2026, at 05:10:45 UTC, when the ASTER TIR instrument was permanently turned off due to power limitations on the Terra spacecraft. More information is available in this NASA Science News Brief.  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. * Data acquisition gaps: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the TIR bands on April 15, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through April 15, 2025, for TIR acquisitions.

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Radiance VNIR and SWIR (AST_09) contains atmospherically corrected data for the Visible and Near Infrared (VNIR) and Shortwave Infrared (SWIR) sensors. Both the VNIR and SWIR data are atmospherically corrected and are generated using the bands of the corresponding ASTER Level 1B image. The AST_09 product has a spatial resolution of 15 meters (m) for the VNIR bands and 30 m for the SWIR bands. Known Issues * Data acquisition gap: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the VNIR bands on January 18, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through January 16, 2025, for VNIR observations. * International date line: Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the Universal Transverse Mercator (UTM) zone defined in the file metadata. * SWIR bands: ASTER SWIR detectors are no longer functioning as of January 12, 2009, due to anomalously high SWIR detector temperatures. * SWIR anomaly: Users are advised that ASTER SWIR data acquired from April 2008 to January 11, 2009, exhibit anomalous saturation of values and anomalous striping. This effect is also present for some prior acquisition periods. Please refer to the ASTER SWIR User Advisory for more details.

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Reflectance VNIR and Crosstalk Corrected SWIR (AST_07XT) dataset contains measures of the fraction of incoming solar radiation reflected from the Earth’s surface to the ASTER instrument corrected for atmospheric effects and viewing geometry for both the Visible and Near Infrared (VNIR) and Shortwave Infrared (SWIR) sensors. Both the VNIR and SWIR data are atmospherically corrected and are generated using the bands of the corresponding ASTER L1B image. The AST_07XT product has a spatial resolution of 15 meters (m) for the VNIR bands and 30 m for the SWIR bands. Known Issues * Data acquisition gap: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the VNIR bands on January 18, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through January 16, 2025, for VNIR observations. * International date line: Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the Universal Transverse Mercator (UTM) zone defined in the file metadata. * SWIR bands: ASTER SWIR detectors are no longer functioning as of January 12, 2009, due to anomalously high SWIR detector temperatures. * SWIR anomaly: Users are advised that ASTER SWIR data acquired from April 2008 to January 11, 2009, exhibit anomalous saturation of values and anomalous striping. This effect is also present for some prior acquisition periods. Please refer to the ASTER SWIR User Advisory for more details.

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 image. Known Issues * Data acquisition gap: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the VNIR bands on January 18, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through January 16, 2025, for VNIR observations. * International date line: Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the Universal Transverse Mercator (UTM) zone defined in the file metadata. * SWIR bands: ASTER SWIR detectors are no longer functioning as of January 12, 2009, due to anomalously high SWIR detector temperatures. * SWIR anomaly: Users are advised that ASTER SWIR data acquired from April 2008 to January 11, 2009, exhibit anomalous saturation of values and anomalous striping. This effect is also present for some prior acquisition periods. Please refer to the ASTER SWIR User Advisory for more details.

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Reflectance VNIR and SWIR (AST_07) data product contains measures of the fraction of incoming solar radiation reflected from the Earth’s surface to the ASTER instrument corrected for atmospheric effects and viewing geometry for both the Visible and Near Infrared (VNIR) and Shortwave Infrared (SWIR) sensors. The AST_07 product has a spatial resolution of 15 meters (m) for the VNIR bands and 30 m for the SWIR bands. Known Issues * Data acquisition gap: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the VNIR bands on January 18, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through January 16, 2025, for VNIR observations. * International date line: Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the Universal Transverse Mercator (UTM) zone defined in the file metadata. * SWIR bands: ASTER SWIR detectors are no longer functioning as of January 12, 2009, due to anomalously high SWIR detector temperatures. * SWIR anomaly: Users are advised that ASTER SWIR data acquired from April 2008 to January 11, 2009, exhibit anomalous saturation of values and anomalous striping. This effect is also present for some prior acquisition periods. Please refer to the ASTER SWIR User Advisory for more details.