AST_09XT v003

ASTER Surface Radiance VNIR and Crosstalk Corrected SWIR


PI: U.S./Japan ASTER Science Team

Description

The ASTER Surface Radiance VNIR and Crosstalk Corrected SWIR (AST_09XT) is a multi-file product that contains atmospherically corrected data 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. Both the VNIR and the SWIR data are atmospherically corrected using the corresponding bands from an ASTER Level 1B image.

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Characteristics

Collection and Granule

Collection

Characteristic Description
CollectionTerra ASTER
DOI10.5067/ASTER/AST_09XT.003
File Size~119 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_Band1 15 meter resolution VNIR Band 1 (0.52 to 0.60 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.676000
VNIR_Band2 15 meter resolution VNIR Band 2 (0.63 to 0.69 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.708000
VNIR_Band3N 15 meter resolution VNIR Band 3 (0.78 to 0.86 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.862000
SWIR_Band4 30 meter resolution SWIR Band 4 (1.600 to 1.700 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.217400
SWIR_Band5 30 meter resolution SWIR Band 5 (2.145 to 2.185 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.069600
SWIR_Band6 30 meter resolution SWIR Band 6 (2.185 to 2.225 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.062500
SWIR_Band7 30 meter resolution SWIR Band 7 (2.235 to 2.285 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.059700
SWIR_Band8 30 meter resolution SWIR  Band 8 (2.295 to 2.365 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.041780
SWIR_Band9 30 meter resolution SWIR Band 9 (2.360 to 2.430 µm) W/m²/sr/μm 16-bit signed integer N/A N/A 0 to 32767 0.031800

There are 3 groups of ancillary data inputs used in the atmospheric correction of ASTER radiance and reflectance:

  1. Ozone data input: The NCEP/TOVS (National Centers for Environmental Prediction/TIROS (Television & Infrared Observation Satellite) Operational Vertical Sounder) data are acquired from a NOAA satellite, and provides the ancillary column ozone data twice daily. This was the default option with the alternative Naval Research Laboratory's (NRL) Ozone Climatology dataset. Starting on April 18, 2005, NOAAs TOVS developed an irreversible instrument problem, and therefore, the use of the NCEP/TOVS ancillary data was discontinued for ASTER Level-1 data acquired from April 18, 2005 onward. This ancillary data source is available for ASTER data acquired prior to April 18, 2005. Currently, the only alternative in use for column ozone is NRLs Ozone Climatology dataset.
  2. Aerosol data input: Presently, NRLs Aerosol Climatology ancillary data are the only available input.
  3. Temperature, Atmospheric pressure, and Moisture Profile data inputs: The source of these data are the NCEP-GDAS (Global Data Assimilation System) available at every 6 hours temporal frequency. The alternative is the NRL Climatology dataset. These datasets are based on modeling, simulation, and prediction, and therefore, they are static, monthly, averaged datasets used only as a last resort.

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_09XT.003

About the Image

Terra ASTER surface radiance band combination 3n-2-1 data from the AST_09XT product over Canada on August 2, 2018.

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