Relevance of field observations as boundary conditions for understanding ice-sheet-ocean interactions

The direct contact of warm ocean water with the front and base of ice shelves is the main driver for accelerated mass loss of the Antarctic ice sheet. We present a compilation of observations from various projects and methodological approaches applied over the last decade along the Dronning Maud Land coast and highlight their importance for understanding the ice-ocean interactions. With a focus on the Ekström ice shelf, these include spatially continuous seismic observations in combination with airborne gravity inversion to yield sub-shelf bathymetry and geomorphological evidence of past ice-flow activity; ice-dynamic numerical modelling to investigate the role of seafloor/subglacial substrate characteristics to enhance or reduce ice-sheet extent and advance/retreat rates; sub-shelf CTD measurements to determine ocean properties driving basal melting; satellitebased remote sensing to determine ice-shelf height changes and spatially-distributed basal melting; and point measurements of basal melt with surface-based phase-sensitive radar to determine ocean-driven melt and validate remote-sensing products. As the Dronning Maud Land coast plays a critical role in preconditioning the water mass of the coastal current before it enters the Filcher ice-shelf cavity, we argue that a coordinated inter- and transdisciplinary observational network is required to facilitate monitoring a potential ice-sheet mass loss in this part of Antarctica

Interpretation of geomorphological features underneath Ekströmisen, Antarctica in their glacio-geological context

The aim of this Master Thesis is to reconstruct the glacio-geological history of the Ekström ice shelf on the basis of subglacial characteristics. This investigation provide clues to past ice dynamics, which may contribute to the valuation of sea level rise due to climate change in subsequent studies. The interpretation of these morphologies at the sea floor was performed with the geophysical methods swath bathymetry, Parasound and reflection seismics. The investigations were supported by the calculation of the sea bed roughness at the seismic profiles. The landforms were used to identify advance and retreat behaviours and phases of still-stand, draw conclusions about the substrate and compare the findings with other Antarctic ice shelves. Channel structures imply the presence of meltwater and thus changes in the thermal regime of the glacier base. The detailed results can contribute to a better understanding of the behaviour and to more reliable estimates for future responses of the East Antarctic ice shelves to environmental change