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Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

Korsgaard NJ, Nuth C, Khan SA, Kjeldsen KK, Bjørk AA, Schomacker A, Kjær KH - Sci Data (2016)

Bottom Line: Supporting data consist of a reliability mask and a photo footprint coverage with recording dates.Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m.This dataset proved successful for topographical mapping and geodetic mass balance.

View Article: PubMed Central - PubMed

Affiliation: Centre for GeoGenetics, Natural History Museum, University of Copenhagen, 1350 Copenhagen, Denmark.

ABSTRACT
Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

No MeSH data available.


Related in: MedlinePlus

Decadal elevation change calculated using the G150 DEM and IPY-SPIRIT SPOT5-HRS3 DEM products.(a) Kangerlussuaq Glacier 1981–2008 and (b) Dauggaard-Jensen Glacier 1987–2014. Note the elevation difference legend has been saturated at −30 m, and elevation difference transects are plotted in the insert show actual values. Analysis of elevation change on Kangerlussuaq Glacier can be found in Khan et al.22 and Kjeldsen et al.24.
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f8: Decadal elevation change calculated using the G150 DEM and IPY-SPIRIT SPOT5-HRS3 DEM products.(a) Kangerlussuaq Glacier 1981–2008 and (b) Dauggaard-Jensen Glacier 1987–2014. Note the elevation difference legend has been saturated at −30 m, and elevation difference transects are plotted in the insert show actual values. Analysis of elevation change on Kangerlussuaq Glacier can be found in Khan et al.22 and Kjeldsen et al.24.

Mentions: We find the completeness of two land coverages, glaciers and ice sheets (Ice/snow) and ice-free terrain/bedrock (Ice-free), by calculating the percentage of successfully resolved heights to the number of posts in each land coverage. Thus, completeness is the percentage of measurements with FOM values in the 40–99 range relative to FOM values in the 2–99 range (Table 4 (available online only)). We use GEOGREEN2 (ref. 12) map data to mask our two land coverage classes so that the coastline makes up the outer boundary and the edge of the innermost strips of aerial photographs makes up the boundary in the interior. The ICE coverage of GEOGREEN2 (ref. 12) is then used to differentiate between Ice/snow and Ice-free terrain/bedrock. The results are shown in Table 7, where it is evident that the ability to resolve heights is impacted by snow and topography. Visual inspection of the reliability masks reveal that low contrast on snow makes it difficult to resolve heights in the interior of ice sheet and glaciers, and in particular the G150 DEM products in the east (1987) and southeast (1981) are affected by this (e.g., Fig. 8). The topography is also more rugged in the east and southeast, with numerous deeply incised valleys and nunataks, which is also reflected in the results for the ice-free terrain.


Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

Korsgaard NJ, Nuth C, Khan SA, Kjeldsen KK, Bjørk AA, Schomacker A, Kjær KH - Sci Data (2016)

Decadal elevation change calculated using the G150 DEM and IPY-SPIRIT SPOT5-HRS3 DEM products.(a) Kangerlussuaq Glacier 1981–2008 and (b) Dauggaard-Jensen Glacier 1987–2014. Note the elevation difference legend has been saturated at −30 m, and elevation difference transects are plotted in the insert show actual values. Analysis of elevation change on Kangerlussuaq Glacier can be found in Khan et al.22 and Kjeldsen et al.24.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862325&req=5

f8: Decadal elevation change calculated using the G150 DEM and IPY-SPIRIT SPOT5-HRS3 DEM products.(a) Kangerlussuaq Glacier 1981–2008 and (b) Dauggaard-Jensen Glacier 1987–2014. Note the elevation difference legend has been saturated at −30 m, and elevation difference transects are plotted in the insert show actual values. Analysis of elevation change on Kangerlussuaq Glacier can be found in Khan et al.22 and Kjeldsen et al.24.
Mentions: We find the completeness of two land coverages, glaciers and ice sheets (Ice/snow) and ice-free terrain/bedrock (Ice-free), by calculating the percentage of successfully resolved heights to the number of posts in each land coverage. Thus, completeness is the percentage of measurements with FOM values in the 40–99 range relative to FOM values in the 2–99 range (Table 4 (available online only)). We use GEOGREEN2 (ref. 12) map data to mask our two land coverage classes so that the coastline makes up the outer boundary and the edge of the innermost strips of aerial photographs makes up the boundary in the interior. The ICE coverage of GEOGREEN2 (ref. 12) is then used to differentiate between Ice/snow and Ice-free terrain/bedrock. The results are shown in Table 7, where it is evident that the ability to resolve heights is impacted by snow and topography. Visual inspection of the reliability masks reveal that low contrast on snow makes it difficult to resolve heights in the interior of ice sheet and glaciers, and in particular the G150 DEM products in the east (1987) and southeast (1981) are affected by this (e.g., Fig. 8). The topography is also more rugged in the east and southeast, with numerous deeply incised valleys and nunataks, which is also reflected in the results for the ice-free terrain.

Bottom Line: Supporting data consist of a reliability mask and a photo footprint coverage with recording dates.Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m.This dataset proved successful for topographical mapping and geodetic mass balance.

View Article: PubMed Central - PubMed

Affiliation: Centre for GeoGenetics, Natural History Museum, University of Copenhagen, 1350 Copenhagen, Denmark.

ABSTRACT
Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

No MeSH data available.


Related in: MedlinePlus