The ASTER Surface Kinetic Temperature (AST_08) is generated using the five Thermal Infrared (TIR) bands (acquired either during the day or night time) between 8 and 12 µm spectral range. It contains surface temperatures at 90 m spatial resolution for the land areas only. Surface kinetic temperature provides a vital input to studies of volcanism, thermal inertia, surface energy, and high-resolution mapping of fires. This product is derived using the same algorithm as the ASTER Surface Emissivity AST_05 Product.
Surface kinetic temperature is determined by applying Planck's Law using the emissivity values from the Temperature/Emissivity Separation (TES) algorithm, which uses atmospherically corrected ASTER surface radiance (TIR) data. The TES algorithm first estimates emissivity in the TIR channels using the Normalized Emissivity Method (NEM). These estimates are used along with Kirchoff's Law to account for the land-leaving TIR radiance that is due to sky irradiance. That figure is subtracted from TIR radiance iteratively to estimate the emitted radiance from which temperature is calculated using the NEM module.
The Science Scalable Scripts-based Science Processor for Missions (S4PM) Version 3.4 algorithm has additional input data options that provide better input data coverage (simultaneously acquired MODIS data versus 6-hourly modeled NCEP input data) and consequently more accurate Level 2 output data. The updated algorithm includes the following improvements:
|File Size||~3 MB|
|Temporal Extent||2000-03-04 to Present|
|Coordinate System||Universal Transverse Mercator (UTM)|
|Datum||World Geodetic System (WGS84)|
|Geographic Dimensions||~60 km x 60 km|
|Number of Science Dataset (SDS) Layers||1|
|Columns/Rows||700 x 830|
|Pixel Size||90 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|KineticTemperature||Surface kinetic temperature composite||Kelvin||16-bit unsigned integer||N/A||N/A||200 to 3200||0.1|
There are three groups of ancillary data inputs used in the atmospheric correction of ASTER Level 2 products:
The AST_08 products do not yet include the OPERATIONALQUALITYFLAGEXPLANATION field in the metadata file to indicate if a fall back has occurred and identify which input source was used to generate the Level 2 product files. A future release will include this metadata attribute information.