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.

The ASTER L2 Surface Emissivity data product is only available through NASA’s Earthdata Search. The ASTER Order Instructions provide step-by-step directions for ordering this product.

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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 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 fall back option 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 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

Access Data

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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