Shuttle Radar Topography Mission
IntroductionSTS-99 mission. The raw data were collected using an instrument named “Spaceborne Imaging Radar-C”. The raw data were later processed and released as usable digital grid files.
Availability from within WindPRO
1. Line Object (with purpose to height contour lines)
2. Elevation Grid Object
In addition to loading the data directly from the EMD online services, WindPRO also supports importing the original *.hgt files that can also be downloaded from other internet sources.
The SRTM data are delivered as gridded data with a spatial resolution of the dataset corresponding to 1 arc second and 3 arc seconds, i.e. approximately 30 m and 90 m distance between grid points. As a part of the processing of the SRTM data from our EMD server, the user has an option of choosing whether the data downloaded should be received as either raw gridded data or converted to height contour lines. In order to use the data for energy yield calculations, the data must be converted to contours.
The original SRTM data are stored as tiles sized 1 degree x 1 degree. From https://lta.cr.usgs.gov/SRTM1Arc/: Please note that tiles above 50° north and below 50° south latitude are sampled at a resolution of 2 arc-second by 1 arc-second.
The coverage is the same in both the 1 arc-second (30 m) and the 3 arc-second (90 m) data as currently distributed from the version windPRO 3.0.
Versions and Data Sources
The difference between various versions is primarily that more error checking and validation is applied at later versions.
In 2014-2015, a 1 arc-second resolution dataset (30 m grid resolution) were made available in the near-global coverage (same coverage as the 3 arc-second dataset). This dataset is now also available in windPRO - in addition to the original dataset in a 3 arc-second resolution (90 m grid resolution). The 1 arc-second and 3 arc-second dataset is available in windPRO 3.0 and later versions.
Our experience with the 1 arc-second dataset shows that this 1-arc-second data does have a higher noise-to-information ratio as compared to the original 3-arc-second dataset. For wind energy applications, EMD recommendends using the 1-arc-second dataset over the 3-arc-second one.
NASA, team around STS-99 and the US public are thanked for making this great digital elevation dataset available in the public domain and thus for aiding the development of renewable energy.
- Original data are available from the NASA website at http://www2.jpl.nasa.gov/srtm.
- More information on SRTM is available at wikipedia at http://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission
- Direct download of 1° x 1° hgt.zip files at http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/
- Direct download of 1° x 1° 1-arc second files at http://earthexplorer.usgs.gov