AST_07XT v003

ASTER Surface Reflectance VNIR and Crosstalk Corrected SWIR


PI: U.S./Japan ASTER Science Team

Description

The 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. Each product delivery includes two Hierarchical Data Format - Earth Observing System (HDF-EOS) files: one for the VNIR, and the other for the SWIR. They are distinguished from one another by a one-second difference in the production time that appears as part of the file name. Both the VNIR and SWIR data are atmospherically corrected and are generated using the bands of the corresponding ASTER L1B image.

AST_07XT is a multi-file product that contains atmospherically corrected data for both the VNIR and SWIR sensors.

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Characteristics

Collection and Granule

Collection

Characteristic Description
CollectionTerra ASTER
DOI10.5067/ASTER/AST_07XT.003
File Size~94 MB
Temporal ResolutionOther
Temporal Extent2000-03-06 to Present
Spatial ExtentGlobal
Coordinate SystemUniversal Transverse Mercator (UTM)
DatumWorld Geodetic System (WGS84)
File FormatHDF-EOS
Geographic Dimensions~60 km x 60 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers9
Columns/Rows4200 (VNIR) and 2100 (SWIR) x 4980 (VNIR) and 2490 (SWIR)
Pixel Size15 m (VNIR) and 30 m (SWIR)

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
VNIR_Band 1 15 meter resolution VNIR Band 1 (0.52 to 0.60 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
VNIR_Band2 15 meter resolution VNIR Band 2 (0.63 to 0.69 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
VNIR_Band3N 15 meter resolution VNIR Band 3 (0.78 to 0.86 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band4 30 meter resolution SWIR Band 4 (1.600 to 1.700 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band5 30 meter resolution SWIR Band 5 (2.145 to 2.185 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band6 30 meter resolution SWIR Band 6 (2.185 to 2.225 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band 7 30 meter resolution SWIR Band 7 (2.235 to 2.285 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band 8 30 meter resolution SWIR Band 8 (2.295 to 2.365 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001
SWIR_Band 9 30 meter resolution SWIR Band 9 (2.360 to 2.430 µm) N/A 16-bit signed integer N/A N/A 0 to 1000 0.001

Known Issues

SWIR Crosstalk Correction The ASTER SWIR sensor is affected by a crosstalk signal scattering problem, a phenomenon discovered after the launch of ASTER aboard the Terra platform in December 1999. The SWIR detector contains 2048 Pt-Si (platinum-silicide) arrays for each of its six spectral bands. There are six pairs of staggered linear CCD arrays for each band that are spaced 1.33 µm apart in the band order 7, 8, 9, 4, 5, and 6. In front of each CCD array pair, there are interference filters that spectrally separate the radiation reflected from the Earth.

Users are advised that ASTER SWIR data acquired from April 2008 to the present 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 Document for more details.

Documentation

Using the Data

E-Learning

View from NASA Terra's Zoom Lens: All About the ASTER Sensor

Tools

Citation

DOI: 10.5067/ASTER/AST_07XT.003

About the Image

Terra ASTER surface reflectance band 1-2-3n data from the AST_07XT product over Canada on August 2, 2018.

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