Abstract
We have used a set of Ground Control Points (GCPs) derived from altimetry measurements from the Ice, Cloud and land Elevation Satellite (ICESat) to evaluate the quality of the 30 m posting ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Global Digital Elevation Model (GDEM) V3 elevation products produced by NASA/METI for Greenland and Antarctica. These data represent the highest quality globally distributed altimetry measurements that can be used for geodetic ground control, selected by applying rigorous editing criteria, useful at high latitudes, where other topographic control is scarce. Even if large outliers still remain in all ASTER GDEM V3 data for both, Greenland and Antarctica, they are significantly reduced when editing ASTER by number of scenes (N≥5) included in the elevation processing. For 667,354 GCPs in Greenland, differences show a mean of 13.74 m, a median of -6.37 m, with an RMSE of 109.65 m. For Antarctica, 6,976,703 GCPs show a mean of 0.41 m, with a median of -4.66 m, and a 54.85 m RMSE, displaying smaller means, similar medians, and less scatter than GDEM V2. Mean and median differences between ASTER and ICESat are lower than 10 m, and RMSEs lower than 10 m for Greenland, and 20 m for Antarctica when only 9 to 31 scenes are included.
Highlights
1.1 ICESat data as Geodetic ControlThe ICESat mission acquired single-beam, globally distributed laser altimeter profiles between ± 86° using the Geoscience Laser Altimeter Sensor (GLAS) (Zwaly et al, 2002 and Schutz et al, 2005)
Changes of the order of millimeters to a few centimeters will have negligible effects on the outcome of these types of evaluations, and no re-processing of the Ground Control Points (GCPs) database has been done with the most recent ICESat data release. This database of ICESat GCPs have been previously used to characterize and quantify spatially varying elevation biases in Digital Elevation Models (DEMs), assessing the accuracy of valuable topographic datasets like GMTED2010 (Global Multiresolution Terrain Elevation Data), developed by the USGS (United States Geological Survey) and NGA (National Geospatial-Intelligence Agency), and previously those produced by sensors like the Shuttle Radar Topography Mission (SRTM) (Carabajal and Harding, 2005 and 2006; Carabajal et al, 2010), and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) (ASTER Validation Team 2009 and 2011)
Accurate global topographic control provided by ICESat has helped establish the accuracy of DEMs and the spatial distribution of elevation biases
Summary
The ICESat mission acquired single-beam, globally distributed laser altimeter profiles between ± 86° using the Geoscience Laser Altimeter Sensor (GLAS) (Zwaly et al, 2002 and Schutz et al, 2005). Changes of the order of millimeters to a few centimeters will have negligible effects on the outcome of these types of evaluations, and no re-processing of the GCP database has been done with the most recent ICESat data release This database of ICESat GCPs have been previously used to characterize and quantify spatially varying elevation biases in Digital Elevation Models (DEMs), assessing the accuracy of valuable topographic datasets like GMTED2010 (Global Multiresolution Terrain Elevation Data), developed by the USGS (United States Geological Survey) and NGA (National Geospatial-Intelligence Agency), and previously those produced by sensors like the Shuttle Radar Topography Mission (SRTM) (Carabajal and Harding, 2005 and 2006; Carabajal et al, 2010), and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) (ASTER Validation Team 2009 and 2011).
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