1 Background - mountain.PROJECTS

TURKU UNIVERSITY DEPARTMENT OF GEOGRAPHY PUBLICATIONS B Nr 4energy and to the area covered by the glacier itself, which brought about additionaldifficulties in the change mapping / documentation.Basic principles for the joint interpretation of glacier rheology and determining the areas ofextreme glacier changes in stereophotogrammetric, radargrammetric, lidargrammetric andinterferometric models were designed and tested. It has been decided that the estimation oflong-term glacier changes should be performed in the geo-coded cartographic products, suchas topographic and / or rheological maps, both available and newly generated. The importanceof identical geometry and comparable contents of multitemporal cartographic products to beused was underlined. It was agreed that all new cartographic products will be generated atscales and cartographic projections typical of national topographic maps (ÖK 50 for Austrianand M711 for Norwegian sites).A novel stereoorthophoto technique was devised and tested for the representation andmeasurement of surficial glacier changes in Hintereisferner. Several original optionsincluding radiometric, atmospheric and topographic corrections were designed and practicallyapplied to detecting marginal glacier changes and analysing the re-distribution of main glacierzones (snow, firn, ice) from the multitemporal high-resolution imagery obtained by the TMand ETM+ sensors from the LANDSAT 4, 5 and 7 as well as from ASTER-TERRA satellites.It was found that, in Engabreen, the determined ELA and the ablation area ratio (AAR)matched well with the field-derived ELA giving the confidence on the methodologydeveloped.The vertical accuracy of reconstructing glacier elevation (surficial) changes from airbornelidar measurements was given as ± 0.5 m. The accuracy of measuring glacier marginalchanges from spaceborne image data in areal terms ranged from ± 0.04 km² for highresolutionIKONOS models to ca. ± 0.15 km² for medium-resolution LANDSAT and ASTERmodels. The positional accuracy tests for the IKONOS orthoimage maps were carried out bycomparing 18 arbitrary stable check points identified in both the orthoimage map sheet andthe existing topographic map sheets ÖK50 in 1:50 000 scale. The root mean squaredifferences between measured co-ordinates is characterised by a value of 16.7 m. The resultsof positional accuracy tests are summarised in Table 3. The correctness of glacier terminiposition and the information contents of the IKONOS satellite image maps were also checkedby direct comparison with the old airborne orthoimages (1998) produced by the Austriannational survey and with the ALTM-4K02 semi-controlled airborne image mosaic.Table 3. Maximum errors between the IKONOS orthoimageand Austrian topographic maps on Hintereisferner.Number of check points 18Mean height of points, m 3358.5Mean difference, m 17.92RMS, m 16.66Short-term glacier changes were detected and measured from interferometric andlidargrammetric models covering both test sites in 1995-1996 and 2001-2003 respectively. Anoriginal phase gradient approach (GINSAR) to glacier rheological modelling and mappingfrom repeat pass SAR interferograms was devised, programmed, tested and validated indifferent glacier environments. The underlying concept, basic algorithms, processional46