Erfassung von Gletschervolumen-Änderungen, Gletscher-Geschwindigkeitsfeldern und Massenflüsse auf der Antarktischen Halbinsel mittels InSAR, digitaler Photometrie und Feldmessungen
Zusammenfassung der Projektergebnisse
During the last years, many signs for changes of the climate system and their possible effects on the glacial systems have been observed in the area of the Antarctic Peninsula. The aims of this research project were to record the changes of the mass budget in different temporal and spatial scales on the Antarctic Peninsula as well as possible changes in velocities. The project aimed at combining field surveys with comprehensive remote sensing studies. During the project runtime, three Antarctic field campaigns were carried out on King George Island in close collaboration with the Institute of Geophysics of the University of Münster, the Alfred Wegener Institut für Polar- und Meeresforschung (AWI), the Instituto Antartico Uruguayo and the Russian Antarctic Program. On each campaign a comprehensive field program was organized including mass balance measurements, glacier velocities, surface elevations, ice thickness, reference points and glacier extent. The measurements form a baseline survey for subsequent years and change detection. On a small ice cap of King George Island (Bellingshausen Dome) with a rather short response time surface elevation changes were determined utilizing differential GPS measurements. Up to 5 m surface lowering were measured in a 3 year period (2004-2007). Repeated velocity measurements (1997/98 to 2007) on the main ice cap showed no sign of changes in speed. The planned analysis of mass changes of small glaciers by digital photogrammetry could not be completed due to problems in access to required reference points as well as access to aerial photography from 1984. However, with the help of differential InSAR technique a velocity field could be derived for the King George Island ice cap as proposed. It is in good agreement with the in-situ measurements. The data sets are currently assembled for a joint publication and assimilated in the ice dynamic model developed at University of Münster. Additionally, the satellite image database for King George Island has been updated and extended and retreat rates are currently computed. For some main tributaries of Wordie Ice Shelf glacier velocities have also been derived. However, during the project runtime a paper was published with a similar analysis for the same area. Our results correspond with this group's observations. For Alexander Island and Wilkins Ice Shelf a substantial remote sensing analysis was undertaken in the project. It comprises the computation of various interferograms, velocity fields for the main tributaries and the southern part of the ice shelf as well as the analysis of time series of SAR satellite images in regard to ice front positions, retreat rates and break-up events, rift and fracture formation as well as general ice shelf structures. We could show that since 1993 fracture formation intensified and that failure zones developed e.g. at ice rises. Although the satellite database did not allow a quantification of changes in glacier velocities, the images show advance of inflowing glaciers to Wilkins Ice Shelf as well as changes in the fringe patterns along the grounding line, that are attributed to changes in velocity structure. However, since these effects are observed for inlets, where the outflow to the ice shelf is blocked by ice rises and islands, it remains unknown which effect this may have on the main ice shelf. Furthermore, this work enabled a fast reaction on the recent break-up events at the end of February and in May 2008, latter being the first break-up event recorded and monitored during austral winter. Most important is the integration of high-resolution imagery from new satellite sensors such as ALOS PALSAR and TerraSAR-X. Only the deep penetration depth of the L-band SAR of ALOS enabled the detection of new fracture formations in July 2007. Monitoring activities are ongoing and coordinated with ESA and DLR. Public media has been alerted by the recent break-up events on Wilkins Ice Shelf. A compilation of media reports can be found on www.zfl.uni-bonn.de. We have provided image analysis and text for the ESA Image of the week (http://www.esa.int/esaEO/SEMMX4R03EF_index_0.html) and the ESA start pages on 13.6.2008 (http://www.esa.int/esaEO/SEMG58VG3HF_index_0.html). Various press articles and TV relate to our analysis e.g. Berliner Zeitung, WDR Lokalzeit Münster, Nature News blog, Science Poles, etc.).
Projektbezogene Publikationen (Auswahl)
- (2005): Glacier velocities on King George Island (Antarctica) determined by differential SAR interferometry. Proceeding of the ESA Fringe Workshop, Frascati, 08 November to 02 December 2005
Moll, A., Braun, M. & Lluberas, A.
- (2006): Determination of glacier velocities on King George Island (Antarctica) by DInSAR. Proceedings of the IEEE Geoscience and Remote Sensing Symposium, Denver 31 July to 04 August 2006
Moll, A. & Braun, M.
- (2007): Radarinterferometrische Untersuchungen mit ERS-1/2 auf der Antarktischen Halbinsel. Dissertation. Mathematisch-Naturwissenschaftliche Fakultät der Universität Bonn
Moll, A.
