N: 60 S: -56 E: 180 W: -180
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) Digital Elevation Model (DEM) version 1 (NASADEM_SSP) dataset, which provides global Shuttle Radar Topography Mission (SRTM) sub-swath elevation data at 1 arc second spacing.
NASADEM data products were derived from original telemetry data from the Shuttle Radar Topography Mission (SRTM), a collaboration between NASA and the National Geospatial-Intelligence Agency (NGA), as well as participation from the German and Italian space agencies. SRTM's primary focus was to generate a near-global DEM of the Earth using radar interferometry. It was a primary component of the payload on space shuttle Endeavour during its STS-99 mission, which was launched on February 11, 2000, and flew for 11 days.
In addition to Terra Advanced Spaceborne Thermal and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) Version 2 data, NASADEM also relied on Ice, Cloud, and Land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) ground control points of its lidar shots to improve surface elevation measurements that led to improved geolocation accuracy. Other reprocessing improvements include the conversion to geoid reference and the use of GDEMs and Advanced Land Observing Satellite Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) AW3D30 DEM, and interpolation for void filling.
NASADEM are distributed in 1 degree latitude by 1 degree longitude tiles and consist of all land between 60° N and 56° S latitude. This accounts for about 80% of Earth's total landmass.
NASADEM_SSP data product layers include radar total correlation, radar volumetric correlation, radar individual images, radar incidence angle (relative to ellipsoid), and radar incidence angle (local). A low-resolution browse image showing sub-swath elevation is also available for each NASADEM_SSP granule.
Product Summary
Citation
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS 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 (s01w048) followed by the Data Take and Orbit Numbers (054_140), Sub-swath Identifier (ss1_d_1_1), and the File Extension/Variable (img).
Publications Citing This Dataset
| Title | Year Sort ascending | Author |
|---|---|---|
| Beyond vertical point accuracy—Assessing inter-pixel consistency in 30 m global DEMs for the arid Central Andes | Purinton, B. |
Variables
Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.
The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| IMG | Radar individual images (10 * log10(actual value) + 128) | Number | uint8 | 0 | N/A | N/A |
| INC | Radar incidence angle local with a non-negative value. | Degree | uint16 | 0 | N/A | 0.01 |
| INC0 | Radar incidence angle relative to ellipsoid with a non-negative value. | Degree | uint16 | 0 | N/A | 0.01 |
| TOT_COR | Radar total correlation with a non-negative value. | N/A | uint16 | 0 | N/A | 0.0001 |
| VOL_COR | Radar volumetric correlation with a non-negative value. | N/A | uint16 | 0 | N/A | 0.0001 |