Eisströme und Schelfeise an der Küste der Amundsen See (West-Antarktis), beobachtet mit ERS-SAR

Abstract

In der vorliegenden Diplomarbeit erfolgte die Beobachtung von Eisströmen und Schelfeisen an der Küste der Amundsen See in der West-Antarktis, unter Verwendung von ERS-SAR-Amplitudenbildprodukten. Bestandteile dieser Beobachtung waren die Erstellung eines Gletscherinventares, die Erstellung von Multitemporalbildern, die Auswertung von Veränderungen der Eisfronpositionen und - schwerpunktmäßig - die Bestimmung von Eisfließgeschwindigkeiten und deren räumlicher und zeitlicher Vergleich.

In this diploma thesis ice streams and ice shelves at the coast of Amundsen Sea were monitored using 47 SAR amplitude images, recorded by ERS satellites between 1992 and 2001. Starting from this data basis a glacier inventory and multi-temporal images were compiled and changes in ice front positions were analysed. The study’s main emphasis was put on the analysis of ice flow velocities and their spatial and temporal comparison. The method applied to find out ice velocities was based on an algorithm which allowed tracking crevasses (semi-automatic feature tracking) imaged in the satellite data. The digitizing of distinctive patterns on the glacier’s surface and their visual tracking yielded unsatisfying results. The monitoring of the ice front positions revealed mainly glacier advances: 23 km regarding Thwaites glacier (1992–2000), 7 km regarding Crosson ice shelf (1995–2000) and 6.5 km regarding Pine Island glacier (1997–2000). Between 1992 and 1997 Pine Island’s ice front was nearly steady state. The analysis of ice flow velocities along trajectories from upper area to terminus resulted overall in 1.0–3.6 km/a for Thwaites glacier (1996–2000), 0.8–3 km/a for Pine Island glacier and 0.2–1.1 km/a for Pope glacier / Crosson ice shelf (each 1995–2000). Both Thwaites and Pine Island glacier accelerated by almost 1 km/a after crossing the grounding line. Furthermore, the implementation of feature tracking revealed the formerly unknown phenomenon that Thwaites glacier tongue rotates around a central point near the grounding line.