Iceberg scours on the Antarctic shelf
Introduction
The objectives of the scour studies are related to the SCAR EASIZ (Scientific Committee on Antarctic Research - Ecology of the Antarctic Sea Ice Zone) program. Field studies were conducted during RV Polarstern cruises in 1996 (EASIZ I), 1998 (EASIZ II) and 2000 (EASIZ III). EASIZ III during R/V Polarstern leg ANT-XVII/3 focused on microscale areas beneath ice shelves. Several joint projects investigated different ecological aspects of Antarctic sea ice environments.
One project deals with the physical influence of grounded icebergs on antarctic benthic fauna as well as other sea-floor communities. Supported by underwater videocameras, remotely operated vehicles (ROV), multiple grabs (MG) and the multi-beam echo sounder Hydrosweep DS-2 areas has been surveyed where benthic environments were expected to be ruined by grounded icebergs. In close interdisciplinary collaboration the current amount of disturbance is to be studied in order to discover potential interactions with climatic changes and related calving rates of icebergs.
Grounded Icebergs
Austaasen Bank
Field of Activity
The area which was studied during expedition ANT-XVII/3 of R/V Polarstern is called Austaasen, located in the southern part of the Weddell Sea, east of Kapp Norvegia.
Due to previous expeditions this area was already known as to be affected because of a great accumulation of grounded icebergs. Multibeam and pseudo sidescan were utilized to identify scour marks caused by icebergs which were closer studied with ROV and MG subsequently.
ANT-XVII/3 - Track line in the Austaasen area, displayed on AWI BCWS sheet 553. [Fahrtverlauf im Austaasen-Gebiet]
Evaluation
The data is analysed within the framework of a diploma thesis. The extension, size and excavation of scour marks should be determined by means of multibeam and sidescan information..
In combination with external information such as sediment samples, videorecording, and sedimentation modelling, further interpretations and statements about the following aspects should be possible:
- Physical properties of the sedimental surface of the marks,
- Statistical distribution of position and depth of the marks,
- Connections to calving rates and activities (shelf ice, continental ice, mass balance),
- Size and type of icebergs,
- Relative differences of age between the marks.
Data examples
 Colour coded hillshade of the study area |
 Scour marks caused by icebergs |