70th EASTERN SNOW CONFERENCE Huntsville, Ontario, Canada 2013

Production of 3D models of the Pasterze Glacier, , using satellite imagery

KLAUS J. BAYR1, DOROTHY K. HALL2, ADAM RIFFLE1, CHRISTOPHER DUNN1

ABSTRACT

Several studies by the authors have been undertaken to show the recession of the Pasterze Glacier in Austria through satellite imagery since the early 1980s. Our own ground truthing in combination with data from the research team of the University of Graz in Austria have been used to conduct a study of the loss of ice volume and thickness of the glacier. One way to show the reduction is with three-dimensional (3D) modeling of the Pasterze Glacier. Two maps were chosen to be analyzed -- one from 1928 and another from 2006. We used the X, Y coordinates and the elevation, Z. Satellite imagery in conjunction with the mapping software Surfer 11 and several different GIS software packages were used to generate 3D models of the glacier. 3D models, such as the one developed for the Pasterze Glacier, can be used to demonstrate loss of ice volume which has resulted from regional climate warming.

Keywords: Pasterze Glacier, digitizing, georeferencing, Ikonos, Landsat ETM+, ARC MAP 10, Surfer 11

INTRODUCTION

We studied the recession of the Pasterze Glacier, Austria, by examining maps showing the glacier extent from 1928 (Österreichische Karte, 1928) and 2006 (Deutscher Alpenverein, 2006). The maps were used to generate 3D models by digitizing along the contour lines. When the two 3D models are compared we can see how much loss there has been since 1928. The new 3D models provide an alternative way to depict the loss and better conceptualize the shrinkage of the glacier. The Pasterze Glacier is the largest glacier in the and within Austria and has a drainage area of over 44 km2. The glacier’s current extent is approximately 8 km; the tongue has receded 1392 m since 1880, and has been receding rapidly since 1928.

______1 Keene State College, 9 Monadnock Court, Keene NH, 03431. 2 Goddard Space Flight Center, NASA, Greenbelt, MD 20771.

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Figure 1: Location of the Pasterze Glacier

BACKGROUND AND METHODOLOGY

The Pasterze Glacier (47o 6’ N, 120 42’ E) flows from the Johannisberg (3463 m) and is located in the Hohe Tauern Range which is part of the Eastern Alps of Austria. The highest peak in Austria, the (3798 m), is located to the southwest of the Pasterze Glacier and its hanging glaciers contribute melt water and morainic material to the glacier. The Pasterze Glacier has retreated significantly since the first time it was mapped in 1864 (Bayr et al., 1994 & 2009).

Figure 2: Pasterze Glacier Sept. 2011. Figure 3: Pasterze Glacier Aug. 1969.

In addition to the 1928 and 2006 maps, satellite imagery from Ikonos, Landsat ETM+ and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have been analyzed and the ground truth measurements were studied and implemented.

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Figure 4: Ikonos image of the Pasterze Glacier (acquired on August 22, 2011).

The first map delineating the terminus of the Pasterze Glacier was published in 1864. The terminus of the glacier has changed in every subsequent map created since, and this is documented in the two maps analyzed for this project from 1928 through 2006. The terminus once reached the Margaritze Reservoir, shown in Figure 4. The maps from 1928 and 2006 were georeferenced to the 33 N UTM and then imported into ArcMap 10 with the Rectify Tool Bar. Using a shape file the x, y, z points were manually digitized along the contour lines. Upon completion the shape file for the 1928 map contained over 6000 points (Fig. 5) and the shape file for the 2006 map contained just over 5000 points.

Figure 5: Digitized points on the 1928 map.

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The points from ArcMap were then exported to an Excel document and opened in the Golden Software program Surfer 11. The Grid file Report was used to create each a 3D model for the 1928 and the 2006 map. Finally the 1928 map was draped over the 1928 3D model (Fig. 6) and the Landsat ETM+ scene over the 2006 3D model (Fig.7). The Landsat ETM+ scene was better suited for draping over the 3D model than were the Ikonos and ASTER scenes.

Figure 6: 3D Model of derived from the 1928 map of the Pasterze Glacier.

Figure 7: 3D Model Draped with 2006 Landsat image.

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DISCUSSION

In-situ measurements were necessary to determine the terminus of the glacier for the 2006 satellite image, while the 1928 map showed fairly clearly where the glacier ended. The reason for this is that the recession of the tongue of the glacier and the lowering of the glacier surface has allowed debris to accumulate on the surface of the remaining ice on the tongue. This debris-covered ice makes it difficult to determine the exact terminus of the glacier tongue. In 1928 the glacier tongue was cleaner because there had been less recession, and therefore it was easier to map the terminus. The GIS programs ARCMAP 10, IDRISI, ENVI and Surfer 11, were used to produce the 3D models. ArcMap 10 was used during the beginning stages of the project for the georeferencing as well as for digitizing along the contour lines. IDRISI which is a much more complex GIS and remote sensing software, offers a wide range of capabilities. However, Surfer 11 was found to be best suited for the construction of the models.

RESULTS

Comparing the 3D models of 1928 and 2006 it is clear that the Pasterze Glacier has undergone a dramatic retreat. One can note by comparing the midsection of the tongue of the two models that the width of the glacier has been reduced as well. In addition, the height of the glacier has lowered as documented in a previous study. On average the glacier tongue has lost 148 m from 1928 to 2006 (Bayr et al. 2009). Through the use of the 3D models and the maps it was possible to construct a profile view of the glaciers, one of 1928 and one of 2006. These profiles were then draped over each other to compare the decrease in the thickness of the ice or the lowering of the glacier’s elevation. This model is shown in Figure 8.

Figure 8: Draped profiles of 1928 and 2006 3D Models (schematic).

CONCLUSION

Globally glaciers have been receding over the past 150 years and glaciers in the European Alps have lost more than 50% of their volume (Haeberli et al. 2000). The Pasterze Glacier has receded since 1864 in response to an increase in air temperature, particularly an increase in average summer temperatures (Bayr et al. 1994). Since 1880 the Pasterze Glacier has receded in length by 1392 m

43 and at an accelerated pace -- approximately 786 m -- since 1965 ( Bayr, et al. 2009). The Pasterze Glacier has retreated in both length and volume significantly from 1928 through 2006. The elevation of the glacier has also lowered. The largest amount of loss is in the ablation area of the glacier. Construction of 3D models and draped profiles of the 3D models is an excellent way to show the glacier extent, volume and elevation changes.

REFERENCES

Bayr, Klaus and Dorothy Hall. 2009. The recession of the Pasterze Glacier, Austria as seen on maps, satellite imagery and measured through ground truthing from 1864 to 2008, Proceedings of the 66th Annual Eastern Snow Conference, Niagara-on-the Lake Ontario, 9-11 June 2009. Bayr, Klaus and Dorothy Hall, 1994. Observations on glaciers in the eastern Austrian Alps using satellite data. International Journal of Remote Sensing 15(9): 1733-1752. Deutscher Alpenverein, 1982, 1992 and 2006. Alpenvereinskarte Nr. 40, Grossglocknergruppe, Innsbruck. Haeberli, W. et al, 2000. Glacier monitoring within the global climate observing system. Annals of Glaciology 31: 241-246. Ikonos, August 22, 2011, po_755073. Landsat ETM+Image , August 20, 2002, Path/Row 193/27 Österreichische Karte, 1864 and 1928, #153. Grossglockner, Bundesamt für Eich-und Vermessungswesen, Wien. University of Graz, Austria: 1965 to 2012, Gletscherberichte (yearly glacier reports) of the Pasterze Glacier, Manuscripts.

Special thanks to: Christopher Brehme, Assistant Professor of Geography, Keene State College, Keene, NH and Monica Grigg from Golden Software, Golden, CO for their support in construction of the 3D models.

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