Description
The Land Processes Distributed Active Archive Center (LP DAAC) is responsible for the archive and distribution of NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) SRTM, which includes the global 3 arc second (~90 meter) sub-sampled product. The 3 arc second data was derived from the 1 arc second using sampling methods. (See Figure 3 in the User Guide)
The NASA SRTM data sets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA - previously known as the National Imagery and Mapping Agency, or NIMA), as well as the participation of the German and Italian space agencies. This collaboration aims to generate a near-global digital elevation model (DEM) of Earth using radar interferometry. SRTM was the primary (and virtually only) payload on the STS-99 mission of the Space Shuttle Endeavour, which launched February 11, 2000 and flew for 11 days.
The SRTMGL3 data were sub-sampled fromSRTM1GL data that fall within that tile. These elevation files use the extension ".HGT", meaning height (such as N37W105.SRTMGL3S.HGT). The primary goal of creating the Version 3 data was to eliminate gaps, or voids, that were present in earlier versions of SRTM data. In areas with limited data, existing topographical data were used to supplement the SRTM data to fill the voids. The source of each elevation pixel is identified in the correspondingSRTMGL3N product (such as N37W105.SRTMGL3N.NUM).
The SRTM swaths extended from ~30 degrees off-nadir to ~58 degrees off-nadir from an altitude of 233 kilometers (km), creating swaths ~225 km wide, and consisted of all land between 60° N and 56° S latitude to account for 80% of Earth's total landmass.
Known Issues
- Known issues in the NASA SRTM are described in the following publication:
- Rodriguez, E., C. S. Morris, and J. E. Belz (2006), A global assessment of the SRTM performance, Photogramm. Eng. Remote Sens., 72, 249–260.https://doi.org/10.14358/PERS.72.3.249
Version Description
Citation
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with theEOSDIS Data Use and Citation Guidance.
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File Naming Convention
The file name begins with the latitude and longitude of the lower left corner of the tile (N00E006) followed by the Data Format (hgt).
Documents
USER'S GUIDE
ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)
GENERAL DOCUMENTATION
Publications Citing This Dataset
Variables
The table below lists the variables contained within a single granule for thisdataset. Variables often contain observed or derived geophysical measurementscollected from a variety of sources, including remote sensing instruments onsatellite and airborne platforms, field campaigns, in situ measurements, andmodel outputs. The terms variable, parameter, scientific data set, layer, and bandhave been used across NASA’s Earth science disciplines; however, variable is thedesignated nomenclature in NASA’s Common Metadata Repository (CMR).Variable metadata attributes such as Name, Description, Units, Data Type, FillValue, Valid Range, and Scale Factor allow users to efficiently process and analyzethe data. The full range of attributes may not be applicable to all variables.Additional information on variable attributes is typically available in the data,user guide, and/or other product documentation.
For questions on a specific variable, please use theEarthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| DEM | Elevation | Meters | int16 | N/A | -32767 to 32767 | N/A |