Updated Global Elevation Data Released by NASA

Caitlin Dempsey

Updated:

A new global digital elevation model (DEM) has been released. NASADEM is a reprocessing of Shuttle Radar Topography Mission (SRTM) data to improve height accuracy and to infill missing elevation data. The data was improved through the use of algorithms and data that wasn’t available at the time of the original SRTM data release. Missing data within SRTM was refined with ASTER GDEM elevations.

Missing data in red, original versus reprocessed SRTM. Height as brightness, Grand Canyon, Arizona, USA. Source: Crippen et al., 2016.
Missing data in red, original versus reprocessed SRTM. Height as brightness, Grand Canyon, Arizona, USA. Source: Crippen et al., 2016.

From NASA‘s technical details about the process:

We will reprocess the entire SRTM dataset from raw sensor measurements with validated improvements to the original processing algorithms. We will incorporate GLAS data to remove artifacts at the optimal step in the SRTM processing chain. We will merge the improved SRTM strip DEMs, refined ASTER and GDEM V2 DEMs, and GLAS data using the SRTM mosaic software to create a seamless, void-filled NASADEM. In addition, we will provide several new data layers not publicly available from the original SRTM processing: interferometric coherence, radar backscatter, radar incidence angle to enable radiometric correction, and a radar backscatter image mosaic to be used as a layer for global classification of land cover and land use.

The newly available NASADEM data products are available with a 1 arc second resolution. Other radar products were released with the updated DEM. All NASADEM products are available for land between 60° N and 56° S latitude, representing 80% of all the Earth’s landmasses. All datasets can be accessed from NASA’s Land Processes DAAC (LP DAAC)

More

NASADEM: Creating a New NASA Digital Elevation Model and Associated Products. (2020, February 18). Retrieved from https://earthdata.nasa.gov/esds/competitive-programs/measures/nasadem

Crippen, R., Buckley, S., Belz, E., Gurrola, E., Hensley, S., Kobrick, M., … & Rosen, P. (2016). NASADEM global elevation model: methods and progress. http://hdl.handle.net/2014/46123

Access 30-Meter SRTM Data Easily With This Point and Click Interface

Derek Watkins has created a simple and easy to use interface for accessing 30-Meter SRTM data.  Arranged in tiles that are 1 degree latitude by 1 degree longitude, Shuttle Radar Topography Mission (SRTM) data was acquired over a 11-day mission in February 2000.  

The mission collected elevation data from 56°S to 60°N and was the highest resolution topographical database at the time of acquisition (more: Mapping the Earth – the Shuttle Radar Topography Mission).

Screenshot from Derek Watkins simple interface for  accessing 30-Meter SRTM data.
Screenshot from Derek Watkins’ simple interface for accessing 30-Meter SRTM data.

Getting 30-meter SRTM from the Tile site is as simple as pointing and clicking.  The map interface is built with Mapbox GL JS as uses tiles from CartoDB.  Overlaid onto the baseman is the SRTM 30-meter index.  Simply pan and zoom (by double-clicking on the map) to the desired area.  Next click on a tile.  

You can then either start grabbing the data or you can preview an image of the DEM.   The SRTM data is packaged as a SRTMHGT files at 1-arc second resolution (3601 x 3601 pixels) and is pulled from NASA’s servers.

Visit: 30-meter SRTM

Looking for 90-meter SRTM data?  Watkins also offers the SRTM Tile Grabber which links to GeoTIFF files created by  CIAT-CSI. These files have been processed to fill data voids and there is a corresponding KMZ file which contains a 90-meter index for growing SRTM data.

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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.

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