Master´s thesis defense by Demola Kayode Abdulai – Niels Bohr Institute - University of Copenhagen

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Master´s thesis defense by Demola Kayode Abdulai


Precise Point Position (PPP) is an absolute positioning technique in satellite navigation whereby a single GPS receiver can be used to obtain position accuracy at the centimeter or decimeter level. It could be used as an alternative to differential positioning techniques (use of two receivers for position accuracy).

Global Positioning System (GPS) data have been acquired with the help of a GPS receiver during a surface GPS Survey in the Northern part of Greenland near the NEEM (North EEMian) drill site from 2007 to 2012. The site is located between the Petermann glacier and the Baffin Bay glacier on a coordinate of 77o 26’55’’N and 55o 03’20’’W. Strain net consisting of 12 stakes at a distance of 2.5km, 7.5km and 25km were setup around a central stake used as the reference pole; it also consisted of four additional stakes at the ridge which were 50km away from the reference pole.

This data have been processed using a Canadian online service called CSRS-PPP to determine the Precise Point Position (PPP) coordinates of the stakes. The PPP result was later used to determine the snow surface elevation and snow accumulation in that region.

In this thesis, part of the GPS data (2009 and 2010) have been re-processed with the Bernese GPS software, version 5.0 to assess the accuracy of Precise Point Positioning (PPP) results previously obtained by the CSRS online services. Orbit related files, Station coordinates files and atmospheric related files were downloaded from the International GNSS Services (IGS) websites and they were included in the PPP analysis with the Bernese software. Observation data corresponding to the same dates from GPS references stations close to the NEEM drill site were also downloaded and included in the processing to improve the results. The reference stations used were KELY, THU3 (Greenland), BARH (United States), NYAL, NYA1 (Norway), REYK (Iceland).