The feasibility of replacing precise levelling with GPS for permafrost deformation monitoring.

摘要

Although several investigations have reported the ability to use GPS to provide several millimetres accuracy to monitor permanent objects, the attainable position accuracy in high latitude areas (∼70 degrees) has not been investigated in detail. The challenges for GPS in this area mainly concern two aspects. First, in the far north, no satellites pass overhead of the observation stations, in which case the satellite geometry is not as good compared to mid-latitude cases. Second, increased ionospheric activity is observed in the north compared to mid-latitudes, and this is particularly exacerbated by the low satellite elevations and subsequent increased path-length of the GPS signals. This leads to increased loss of signal (cycle slips) as well as path delays due to the ionospheric activity. In order to investigate the highest attainable accuracy of GPS in the far north, especially for the height component, two GPS campaigns were carried out in a selected area in the summers of 2003 and 2004. (Abstract shortened by UMI.)