Measurements of fracture toughness applying a four-point-bending technique of ice core B34 from Kohnen Station, Dronning Maud Land, Antarctica

The critical fracture toughness is a material parameter describing the resistance of a cracked body to further crack extension. It is an important parameter to simulate and predict the break-up behaviour of ice shelves from calving of single icebergs to the disintegration of entire ice shelves over a wide range of length scales. The fracture toughness values are calculated with equations that are derived from an elastic stress analysis. Additionally, an X-ray computer tomography (CT scanner) was used to identify the density as a function of depth. The critical fracture toughness of 91 Antarctic inland ice samples with densities between 840 to 870 kg/m**3 has been determined by applying a four-point-bending technique on single edge v-notched beam samples. The examined ice core was drilled 70m north of Kohnen Station, Dronnning Maud Land (75°00' S, 00°04' E, 2882 m).

Snow height on sea ice and sea ice drift from autonomous measurements from buoy 2013S8, deployed during POLARSTERN cruise ANT-XXIX/6 (PS81)

Snow height was measured by the Snow Depth Buoy 2013S8, an autonomous platform, drifting on Antarctic sea ice, deployed during POLARSTERN cruise ANT-XXIX/6 (PS81). The resulting time series describes the evolution of snow height as a function of place and time between 2013-07-09 and 2014-01-05 in sample intervals of 1 hour. The Snow Depth Buoy consists of four independent sonar measurements representing the area (approx. 10 m**2) around the buoy. The buoy was installed on first year ice. In addition to snow height, geographic position (GPS), barometric pressure, air temperature, and ice surface temperature were measured. Negative values of snow height occur if surface ablation continues into the sea ice. Thus, these measurements describe the position of the sea ice surface relative to the original snow-ice interface. Differences between single sensors indicate small-scale variability of the snow pack around the buoy. The data set has been processed, including the removal of obvious inconsistencies (missing values). Records without any snow height may still be used for sea ice drift analyses.

Snow height on sea ice and sea ice drift from autonomous measurements from buoy 2013S7, deployed during POLARSTERN cruise ANT-XXIX/6 (PS81)

Snow height was measured by the Snow Depth Buoy 2013S7, an autonomous platform, drifting on Antarctic sea ice, deployed during POLARSTERN cruise ANT-XXIX/6 (PS81). The resulting time series describes the evolution of snow height as a function of place and time between 2013-07-06 and 2013-09-13 in sample intervals of 1 hour. The Snow Depth Buoy consists of four independent sonar measurements representing the area (approx. 10 m**2) around the buoy. The buoy was installed on first year ice. In addition to snow height, geographic position (GPS), barometric pressure, air temperature, and ice surface temperature were measured. Negative values of snow height occur if surface ablation continues into the sea ice. Thus, these measurements describe the position of the sea ice surface relative to the original snow-ice interface. Differences between single sensors indicate small-scale variability of the snow pack around the buoy. The data set has been processed, including the removal of obvious inconsistencies (missing values). Records without any snow height may still be used for sea ice drift analyses.

Paleomagnetic measurements of 10 sediment profiles from the Antarctic continental slope

Die im Rahmen des zweijährigen Forschungsprojekts über paläomagnetisch-sedimentologische Analysen sedimentärer Zyklen in der Weddell See und ihre stratigraphische Interpretation durchgeführten Arbeiten lieferten Ergebnisse zur Geschichte glaziomariner Sedimentationsprozesse am antarktischen Kontinentalrand. So konnte für ein Kernprofil mit einer außergewöhnlichen Terassenstruktur eine fazielle Gliederung und stratigraphische Einordnung erreicht werden, die auch auf größere Areale in der Weddell See anwendbar sind. Aufgrund der stratigraphischen Randbedingungen konnten die gewonnenen paläo- und gesteinsmagnetischen Messungen in eine Altersstruktur integriert und zusammen mit den sedimentologischen Parametern im Hinblick auf lokale und regionale Umweltveränderungen interpretiert werden. Insbesondere die gesteinsmagnetischen Analysen haben gezeigt, daß die magnetische Kornfraktion als accessorischer Bestandteil im Gesamtsediment dennoch an die Sortierungsprozesse des terrigenen Sedimenteintrags gekoppelt ist. Die ungewöhnlich deutlichen Variationen korngrößenabhängiger Parameter zeigten weiterhin, daß in Verbindung mit einer hochauflösenden Stratigraphie die magnetische Detailanalyse und ein besseres Verständnis der Sedimentationsprozesse in der Nähe der Schelfeiskante und speziell bei Meeresspiegeltiefständen die Möglichkeit eröffnen, unmittelbar Aussagen über die Bewegungen der Schelfeise und die Qualität der Meereisbedeckungen zu machen. Die gezielte Fortsetzung dieser Arbeiten in anderen Arealen am antarktischen Kontinentalrand ist daher wünschenswert. Die verwendeten Verfahren lassen sich mit den derzeit verfügbaren Instrumenten noch erweitern und versprechen durch die sehr sensitive Methodik detaillierte Aussagen zu glaziomarinen Sedimentationsprozessen.