SRTMUS1N: United States Terrain Source Metadata

NASA Shuttle Radar Topography Mission United States 1 arc second number (SRTMUS1N) provides ancillary metadata files for the SRTM digital elevation model over the United States. The separate '.NUM' files indicate the source of each DEM pixel, specifying whether it came from SRTM radar data or ASTER imagery and the number of data takes or scenes used. This collection was retired in 2014, with its data superseded by the global SRTMGL1N product.

Use Cases

• Assessing data quality and reliability by analyzing the source (SRTM vs. ASTER) for each elevation pixel.
• Weighting or filtering elevation data based on the number of contributing SRTM data takes (up to 24) or ASTER scenes (up to 100).
• Fusing multi-source elevation datasets by using the source indicator to resolve conflicts or prioritize specific sensors.

Strengths

• Provides pixel-level provenance for a foundational global DEM dataset, sourced from the NASA MEaSUREs program.
• Data collection involved international collaboration between NASA, NGA, and German and Italian space agencies using dedicated Space Shuttle mission STS-99.

Limitations

• Dataset is retired and no longer maintained, with users directed to the newer SRTMGL1N product.
• Specific row count, file size, and column structure are not provided in the available metadata.
• Conflicting 'last updated' dates exist across platforms (2000 vs. 2026), suggesting potential metadata inconsistencies.

Provenance

Source

NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, Land Processes Distributed Active Archive Center (LP DAAC).

Collection Method

Generated from radar interferometry data collected by the Shuttle Radar Topography Mission (SRTM) aboard Space Shuttle Endeavour (STS-99), launched February 11, 2000.

Time Range

Primary data collection occurred during the 11-day STS-99 mission in February 2000.

Freshness

The dataset collection was retired on November 20, 2014.

Geography

Covers land within the United States, between 60 degrees north and 56 degrees south latitude.