1 Background - mountain.PROJECTS

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TURKU UNIVERSITY DEPARTMENT OF GEOGRAPHY PUBLICATIONS B Nr 4included in the processing of 25 new GCP co-ordinates. 16 of these GCPs have beenestablished by NVE, Oslo. The remaining nine GCPs have been established by the NorwegianMapping Authority. The co-ordinate processing is based on three fixed points (J15 T33, J14T174 and K15 T77) yielding adequate precision, which are part of the Norwegian nationalnetwork.The vector map measured is shown in Figure 14. GPS calculations were performed at NVEusing standard software for this purpose. For the initial calculation of the vectors, AOSS v.2was used (Ashtech Office suite for Survey) which is provided by Magellan products for usewith Ashtech GPS receivers, which is the type mainly used in the GCP measurements. Thesoftware was created by Spectra Precision Terrasat GmbH. For the calculation of the coordinatesthemselves, the block adjustment, VG-land 11.20 was used. This software isprovided by Norkart and is one of the main software packages used for co-ordinatecalculations in Norway.Figure 14. Vectors measured for GCP network around Svartisen study areas.GCP network – AustriaThe points measured for the ground control network are shown in Figure 15. The co-ordinatetransformation was done using only three points, situated very close to each other. TheMolodensky-Badekas transformation was used in the Leica Ski-pro programme.24
PETRI PELLIKKA AND KARI KAJUUTTI (ED)Checking of the calculation was done using five different sets of points, Helmerttransformation and Pinnacle program. The differences in results between the different sets arelarge making the reliability of the transformation questionable. It is evident and also followsfrom the theoretical rules, that there should be more than three fixed points to determine thetransformation parameters. The fixed points should surround the new points and they shouldbe situated far enough from each other. The existing point coverage is too sparse.After some calculations at the Helsinki University of Technology it became clear, that therewas a shift of 1.5 m in height in the GCP co-ordinates. This was then compensated directly inthe co-ordinates, but should be taken into account in coming projects by doing themeasurements again on a broader area and based on a proper geoid model.Figure 15. Ground control points in the vicinity of Hintereisferner (HEF). The light gray spotsindicate buildings and darker ones ground points.Radio-echo sounding - NorwayNo new radio-echo sounding measurements were performed on Svartisen, as radarmeasurements had previously been performed on Engabreen from helicopter and on theground in the 1990s. However, these measurements were not easily accessible for use inOMEGA, partly because they were in the wrong co-ordinate system (NGO instead of UTM).They were re-calculated into the correct co-ordinates and made more easily available for usewithin OMEGA (Figure 16). The ice thickness on the tongue of Engabreen is shown inFigure 17.25
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