Geography Reference
In-Depth Information
Fig. 4.3 Comparison of the
spectral coverage between
LANDSAT-sensors (MSS,
TM, and ETM+) and the
ASTER-sensor
to Level-1B). ASTER-L1A data are officially classified as reconstructed, unpro-
cessed data at full resolution. They contain the image data, the radiometric
coefficients, the geometric coefficients and other supplementary data without
applying the coefficients to the image data, thus keeping the original data values.
The L1B-data are produced by applying the coefficients for radiometric calibration
and geometric resampling. All gained 1A and 1B scenes are transferred to the
EOSDIS archive at the EROS Earth Data Center's EDC Land Processes Distrib-
uted Active Archive Center (LP-DAAC), for storage, distribution and processing
to higher-level data products. All ASTER-data products are stored in a specific
implementation of Hierarchical Data Format called HDF-EOS.
ASTER's geometric system correction mainly contains the rotation and the
coordinate transformation of the line of sight vectors of the detectors to the
coordinate system of the Earth. This is done as part of ASTER-Level-1 processing
at GDS using extra engineering data from the sensor and similar auxiliary data
from the spacecraft platform. The geometric correction of ASTER has developed
in two complex processes of both pre-flight and post-launch calibration. Tests have
proven that ASTER has superb radiometric, geometric and spectral functioning
(Ono et al. 1996 ) (Fig. 4.4 ).
The main scientific purpose of the ASTER-mission is to gain better knowledge
of the local and regional scale processes happening on or near the Earth's surface
and lower atmosphere, as well as the relations between the Earth surface and the
atmosphere. Special applications are: (1) earth surface climatology; (2) vegetation
and ecosystem dynamics; (3) volcano observing; (4) hazard observing; (5) aerosols
and clouds; (6) carbon cycling in the marine ecosystem; (7) hydrology; (8) geology
and soil; and 9) LULC-change (Yamaguchi et al. 1999 ).
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