ASTGTM v003

ASTER Global Digital Elevation Model 1 arc second


PI: U.S./Japan ASTER Science Team

Description

The ASTER Global Digital Elevation Model (GDEM) Version 3 (ASTGTM) provides a global digital elevation model (DEM) of land areas on Earth at a spatial resolution of 1 arc second (approximately 30 meter horizontal posting at the equator).

The development of the ASTER GDEM data products is a collaborative effort between National Aeronautics and Space Administration (NASA) and Japan’s Ministry of Economy, Trade, and Industry (METI). The ASTER GDEM data products are created by the Sensor Information Laboratory Corporation (SILC) in Tokyo.

The ASTER GDEM Version 3 data product was created from the automated processing of the entire ASTER Level 1A archive of scenes acquired between March 1, 2000, and November 30, 2013. Stereo correlation was used to produce over one million individual scene based ASTER DEMs, to which cloud masking was applied. All cloud screened DEMs and non-cloud screened DEMs were stacked. Residual bad values and outliers were removed. In areas with limited data stacking, several existing reference DEMs were used to supplement ASTER data to correct for residual anomalies. Selected data were averaged to create final pixel values before partitioning the data into 1° by 1° tiles with a one pixel overlap. To correct elevation values of water body surfaces, the ASTER Global Water Bodies Database (ASTWBD) Version 1 data product was also generated.

The geographic coverage of the ASTER GDEM extends from 83° North to 83° South. Each tile is distributed in GeoTIFF format and projected on the 1984 World Geodetic System (WGS84)/1996 Earth Gravitational Model (EGM96) geoid. Each of the 22,912 tiles in the collection contain at least 0.01% land area.

Provided in the ASTER GDEM product are layers for DEM and number of scenes (NUM). The NUM layer indicates the number of scenes that were processed for each pixel and the source of the data.

While the ASTER GDEM Version 3 data products offer substantial improvements over Version 2, users are advised that the products still may contain anomalies and artifacts that will reduce its usability for certain applications.

Characteristics

Improvements/Changes from Previous Versions

  • Expansion of acquisition coverage to increase the amount of cloud free input scenes from about 1.5 million in Version 2 to about 1.88 million scenes in Version 3.
  • Separation of rivers from lakes in the water body processing.
  • Minimum water body detection size decreased from 1 square kilometer (km²) to 0.2 km².

Collection and Granule

Collection

Characteristic Description
CollectionTerra ASTER
DOI10.5067/ASTER/ASTGTM.003
File Size~25 MB
Temporal ResolutionMulti-Year
Temporal Extent2000-03-01 to 2013-11-30
Spatial ExtentGlobal
Coordinate SystemGeographic Latitude and Longitude
DatumWGS84/EGM96
File FormatGeoTIFF
Geographic Dimensions1 degree lat x 1 degree lon

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers2
Columns/Rows3601 x 3601
Pixel Size30 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
DEM Digital Elevation Model Meters 16-bit signed integer -9999 N/A -500 to 9000 (0 at sea level) N/A
NUM¹ Number of scenes Number 16-bit signed integer N/A N/A 0 to 250 N/A

¹The contents of the NUM file indicate number of DEM tiles used and the source of the data.

Reference Data for Number of Scenes Layer

Value Description
0-50 GDEM V3 (0 to 50+ scenes)¹
60-110 GDEM V2 (0 to 50+ scenes)¹
131-184 PRISM (1 to 54 scenes)
201-223 SRTM (1 to 23 swaths)
231 SRTM V3 from initial GDEM V3
232 SRTM V2 from initial GDEM V3
233 SRTM V2 from GDEM V2
234 SRTM with NGA fill from GDEM V2
241 NED from GDEM V2 (USA)
242 NED from initial GDEM V3 (USA)
243 CDED from GDEM V2 (Canada)
244 CDED from initial GDEM V3 (Canada)
245 Alaska DEM from GDEM V2
246 Alaska DEM from initial GDEM V3
250 Interpolated

¹ 0 = Unspecified

List of abbreviations: PRISM = Advanced Land Observing Satellite (ALOS) Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), SRTM = Shuttle Radar Topography Mission, NGA = National Geospatial-Intelligence Agency, NED = United States Geological Survey (USGS) National Elevation Dataset, CDED = Canadian Digital Elevation Data, Alaska DEM = USGS 3D Elevation Program (3DEP) Alaska DEM

Product Quality

Quality information is provided in Section 7 of the User Guide.

Known Issues

  • ASTER GDEM Version 3 tiles overlap by one pixel to the north, south, east, and west of the tile perimeter. In most cases the overlapping edge pixels have identical pixel values, but it is possible that in some instances values will differ.
  • ASTER GDEM Version 3 is considered to be void free except for Greenland and Antarctica.
  • Users are reminded that because there are known inaccuracies and artifacts in the dataset, to use the product with awareness of these limitations. The data are provided "as is" and neither NASA nor METI/Earth Resources Satellite Data Analysis Center (ERSDAC) will be responsible for any damages resulting from use of the data.

Documentation

Using the Data

Tools

Citation

DOI: 10.5067/ASTER/ASTGTM.003

About the Image

ASTER Global Digital Elevation Model 1 arc second data over Northern China between March 1, 2000 and November 30, 2013