ECOGIS - Elevation Changes Of the Greenland Ice Sheet

  • Madsen, Søren Nørvang (Project Manager)
  • Dall, Jørgen (Project Participant)
  • Grinder-Pedersen, Jan (Project Participant)
  • Mohr, Johan Jacob (Project Participant)

    Project Details


    ECOGIS is a joint project between the National Survey and Cadastre (KMS), the Geophysical Dept., University of Copenhagen, and DCRS. The project addresses studies of elevations and their changes over the Greenland Ice Sheet on a multidisciplinary basis, employing geodetic field measurements, satellite and airborne altimetry and interferometric synthetic aperture radar (SAR).
    The DCRS contribution primarily concerns the acquisition, processing and calibration of airborne interferometric SAR data acquired with EMISAR ( from the Geikie Plateau near Scoresbysund for generation of a digital elevation model (DEM). The elevation of the plateau is about 2200 m. DCRS also provides expertise in processing of interferometric satellite SAR data in relation to a full time Ph.D. study financed by the project.
    In 1996, 1997, and 1998 KMS and DCRS deployed corner reflectors on the plateau and determined their positions with differential GPS in order to enable a DEM calibration adjustment/verification. During the flight campaigns to Greenland, SAR data were acquired from a 60 km by 25 km area, and kinematic GPS experiments were conducted in order to enable the position of the aircraft to be estimated with an absolute accuracy of about one decimeter. Unfortunately, the EMISAR campaign in 1996 was cancelled due to an aircraft crash.
    The calibration in the overlap regions of the mosaic has been evaluated. In 1998 the systematic errors were up to ±4 meters, but a new algorithm extracting calibration information from the DEM differences in the overlap regions has almost eliminated these errors, and the total RMS error (deterministic plus stochastic) now amounts to about 2 meters. The SAR DEMs have also been compared to those derived from airborne laser altimetry. The differences show that the SAR penetrates 5-10 meters into the ice at altitudes above about 2100 m depending on the temperature, and this consists with the penetration depths observed at the reflectors.
    Effective start/end date01/01/199631/12/1999


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