AST_05 v003

ASTER L2 Surface Emissivity


PI: U.S./Japan ASTER Science Team

Description

The ASTER Surface Emissivity (AST_05) is produced using the Temperature/Emissivity Separation (TES) algorithm for the five Thermal Infrared (TIR) 90 meter bands, acquired during the day or night. The product is comprised of per-pixel emissivity measurements generated over land in addition to embedded metadata and quality assurance data planes.

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Characteristics

Improvements/Changes from Previous Versions

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:

  • A new option has been added to use MODIS Version 6.1 (MOD07_L2) Temperature, Water Vapor, and Pressure inputs. The default order option will remain as National Centers for Environmental Prediction (NCEP)/Global Data Assimilation System (GDAS).
  • The default for the Ozone input data was switched from NCEP/Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) to the new Total Ozone Analysis using Solar Backscatter UltraViolet Version 2 (SBUV/2) and TOVS (TOAST)/Earth Probe-Total Ozone Mapping Spectrometer (EPTOMS) option.
  • The Level 2 algorithm has been updated to provide a fall back option for the Temperature/Water Vapor/Pressure and Ozone input selections. Both selections will automatically revert to the next lower input if the selected input is not available.
    • The Temperature/Water Vapor/Pressure input will fall back from MOD07 to NCEP/GDAS then to Climatology.
    • The Ozone input will fall back from TOAST/EPTOMS to OZ_DLY/TOVS then to Climatology.

Collection and Granule

Collection

Characteristic Description
CollectionTerra ASTER
DOI10.5067/ASTER/AST_05.003
File Size~9 MB
Temporal ResolutionOther
Temporal Extent2000-03-04 to Present
Spatial ExtentGlobal
Coordinate SystemUniversal Transverse Mercator (UTM)
DatumWorld Geodetic System (WGS84)
File FormatHDF-EOS or GeoTIFF
Geographic Dimensions~60 km x 60 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers5
Columns/Rows700 x 800
Pixel Size90 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
TIR_Band10 90 meter resolution TIR Band 10 (8.125 to 8.475 µm) N/A 16-bit unsigned integer N/A N/A 0 to 65535 0.001
TIR_Band11 90 meter resolution TIR Band 11 (8.475 to 8.825 µm) N/A 16-bit unsigned integer N/A N/A 0 to 65535 0.001
TIR_Band12 90 meter resolution TIR Band 12 (8.925 to 9.275 µm) N/A 16-bit unsigned integer N/A N/A 0 to 65535 0.001
TIR_Band13 90 meter resolution TIR Band 13 (10.25 to 10.95 µm) N/A 16-bit unsigned integer N/A N/A 0 to 65535 0.001
TIR_Band14 90 meter resolution TIR Band 14 (10.95 to 11.65 µm) N/A 16-bit unsigned integer N/A N/A 0 to 65535 0.001

There are three groups of ancillary data inputs used in the atmospheric correction of ASTER Level 2 products:

  1. Ozone data input: The default for the Ozone input data is the new Total Ozone Analysis using Solar Backscatter UltraViolet Version 2 (SBUV/2) and TOVS (TOAST)/Earth Probe-Total Ozone Mapping Spectrometer (EPTOMS) option. The fall back option is the National Centers for Environmental Prediction (NCEP)/Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS). The NCEP/TOVS data are acquired from a NOAA satellite, and provides the ancillary column ozone data twice daily. The second fall back option is the Naval Research Laboratory's (NRL) Ozone Climatology dataset.
  2. Aerosol data input: The NRL Aerosol Climatology ancillary data are the only available input.
  3. Temperature, Atmospheric pressure, and Moisture Profile data inputs: Simultaneously acquired MODIS Version 6.1 (MOD07_L2) Temperature, Water Vapor, and Pressure inputs were added as a new option on October 23, 2019. The default order option will remain as the NCEP-Global Data Assimilation System (GDAS) which is available every 6 hours. The second alternative is the NRL Climatology data which are based on modeling, simulation, and prediction. They are static, monthly, averaged datasets, therefore, used only as a last resort.

Known Issues

The AST_05 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.

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_05.003

About the Image

Terra ASTER Surface Emissivity band 14 data from the AST_05 product over Baffin Island, Canada between March 1, 2000 and November 30, 2013.

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