Download pdf of ASTER chapter from Eurimage Products and Services Guide
Note: DN Value Saturation for SWIR Data: the SWIR detector temperature is currently increasing. This could lead to a saturation of DN values for Band 5 ~ 9 SWIR data. Therefore, we highly recommend that those who are especially interested in the data with a high solar elevation or of a high reflectance target use, as much as possible, the data acquired before April 2007.
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), built by a consortium of Japanese government, industry, and research groups, is one of 5 instruments aboard the Terra platform, launched in December, 1999. The combination of wide spectral coverage and high spatial resolution allows ASTER to discriminate amongst a large variety of surface materials, ideal for geological studies, vegetation and ecosystem dynamics, hazard monitoring.
ASTER Sensor Summary
The ASTER instrument has three spectral bands in the visible near-infrared (VNIR), six bands in the short-wave infrared (SWIR), and five bands in the thermal infrared (TIR) regions, with 15, 30, and 90 meters ground resolution respectively. The VNIR subsystem is specifically endowed with a backward-viewing telescope for high-resolution stereoscopic observation in the along-track direction (3B).
The ASTER instrument is unique in two respects: one, it provides multispectral thermal infrared data of high spatial resolution, and also the highest spatial resolution surface spectral reflectance, temperature and emissivity data of all the Terra instrument sensor systems; and two, because of its limited duty cycle, data are acquired to fulfill on-demand data acquisition requests. The ASTER data products include relative spectral reflectance and emissivity, surface radiance, temperature, reflectance and emissivity, brightness temperature-at-sensor, and digital elevation models. ASTER data cover a wide array of application areas including: geology and soils, vegetation and ecosystem dynamics, hazards monitoring (volcanoes, wildfires, floods, landslides, and coastal erosion), land surface climatology, hydrology, and land cover change.
Comparison: ASTER/Landsat 7
Each ASTER scene covers an area of 60 x 60 km.
The standard products made in Japan are as follows:
ASTL1A: (Level 1A) data has SWIR parallax correction, or inter-telescope geometric correction, applied. Geometric coefficients and radiometric coefficients are appended but not applied. Ancillary data of the satellite and engineering data of the ASTER radiometer are also attached.
ASTL1B: (Level 1B) The geometric and radiometric corrections are performed on Level 1A products using a specific map projection (UTM/WGS84). This digital data includes the data of all ASTER sensors.Band-to-band registration within and between the sensors is also performed.
All the Level 2 products are generated from Level 1B.
AST2B01 Surface Radiance: VNIR (AST2B01V), SWIR (AST2B01S),
and TIR (AST2B01T) images have resolutions of 15m, 30m and 90m, respectively.
The unit of surface radiance is W/m2/sr/m.
After atmospheric correction is applied, surface radiance of scenes taken
on a sunny day is calculated. Surface temperature and water vapour data are
necessary for processing the surface radiance, so this processing can be
applied only to pixels without clouds.
Atmospheric correction improves surface identification by applying corrections for position and atmospheric conditions between the satellite and the earth. Although SWIR observation usually takes place during the daytime, it is also possible to observe at night if the surface temperature is high enough (e.g. due to volcanic activity, fires etc.)
See pdf of ASTER chapter from Eurimage Products and Services Guide for complete details of ASTER products
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