Description: Bathymetry (seafloor depth), is a critical parameter providing the geospatial context for a multitude of marine scientific studies. Since 1997, the International Bathymetric Chart of the Arctic Ocean (IBCAO) has been the authoritative source of bathymetry for the Arctic Ocean. IBCAO has merged its efforts with the Nippon Foundation-GEBCO-Seabed 2030 Project, with the goal of mapping all of the oceans by 2030. Here we present the latest version (IBCAO Ver. 4.0), with more than twice the resolution (200 × 200 m versus 500 × 500 m) and with individual depth soundings constraining three times more area of the Arctic Ocean (∼19.8% versus 6.7%), than the previous IBCAO Ver. 3.0 released in 2012. Modern multibeam bathymetry comprises ∼14.3% in Ver. 4.0 compared to ∼5.4% in Ver. 3.0. Thus, the new IBCAO Ver. 4.0 has substantially more seafloor morphological information that offers new insights into a range of submarine features and processes; for example, the improved portrayal of Greenland fjords better serves predictive modelling of the fate of the Greenland Ice Sheet.

Description: The SCAR expert group on the International Bathymetric Chart of the Southern Ocean (IBCSO) was inaugurated in 2004. IBCSO is a regional mapping project of the General Bathymetric Chart of the Ocean (GEBCO) under the joint auspices of the Intergovernmental Oceanographic Commission (IOC) (of UNESCO) and the International Hydrographic Organization (IHO). The project aim was to create the first seamless bathymetric compilation for the entire Southern Ocean south of 60°S. In 2013, finally the first Version of IBCSO was published in the Journal Geophysical Research Letters (Arndt et al., 2013). IBCSO Version 1.0 is a prime example for an international collaboration in Antarctic Science. Over 30 institutions from 15 countries contributed data and shared their expertise to generate the, so far, largest database of bathymetric data of the Southern Ocean. From this database a digital bathymetric model (DBM) was produced. The DBM covers the entire Antarctic Treaty area in a resolution of 500 m. It is available in several formats and projections. In addition, a new map has been created of the Southern Ocean and Antarctica and now is also available to the SCAR community. Both, the DBM and the map, can be downloaded free of charge from the IBCSO web site (www.ibcso.org). In my poster presentation I will present the map product of the IBCSO project and give information about its included data sets, its distribution and its design.

Description: The SCAR expert group on the International Bathymetric Chart of the Southern Ocean (IBCSO) was inaugurated in 2004. IBCSO is a regional mapping project of the General Bathymetric Chart of the Ocean (GEBCO) under the joint auspices of the Intergovernmental Oceanographic Commission (IOC) (of UNESCO) and the International Hydrographic Organization (IHO). The project aim was to create the first seamless bathymetric compilation for the entire Southern Ocean south of 60°S. In 2013, finally the first Version of IBCSO was published in the Journal Geophysical Research Letters (Arndt et al., 2013). IBCSO Version 1.0 is a prime example for an international collaboration in Antarctic Science. Over 30 institutions from 15 countries contributed data and shared their expertise to generate the, so far, largest database of bathymetric data of the Southern Ocean. From this database a digital bathymetric model (DBM) was produced. The DBM covers the entire Antarctic Treaty area in a resolution of 500 m. It is available in several formats and projections. In addition, a new map has been created of the Southern Ocean and Antarctica and now is also available to the SCAR community. Both, the DBM and the map, can be downloaded free of charge from the IBCSO web site (www.ibcso.org). In my presentation I will give an overview of the IBCSO V1.0 compilation methods and highlight the improvements of the IBCSO DBM compared to global datasets. Furthermore, some tips and hints for the usage of IBCSO including the use of the Source Identifier grid (SID) will be given.

Description: The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-Antarctic waters south of 60° S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Oceans (GEBCO). IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 x 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at http://dx.doi.org/10.1594/PANGAEA.805736

Description: High-resolution swath bathymetric data can provide clues to the geological history by revealing the seafloor geomorphology. Submarine glacial landforms, for example, can be used to reconstruct past ice sheet development and landslide debris may reveal areas of past tsunami formation. Here, a geomorphological investigation of swath bathymetric data acquired on five research expeditions of RV Polarstern in three glacier outlet systems of East Greenland (Kejser Franz Joseph Fjord, Kong Oscar Fjord, and Scoresby Sund) will be presented. The investigation refines the, so far, only poorly resolved reconstruction of East Greenland ice sheet development and, in addition, reveals a site of a large rock fall that most probably caused a major tsunami. Combination of the marine geomorphological record with published geological data was used to infer the post-LGM ice dynamics and extent in the study area. The investigation suggests that most ice streams likely reached the shelf edge, via cross-shelf troughs, in all three glacier-outlet systems, probably during the LGM. Ice marginal landforms on the shelf and at the fjord entrances indicate a dynamic ice margin with still stands, retreat phases and subsequent readvances. A tentative chronology was developed based on the geomorphological constraints and the geological record. It suggests that in the Allerød-Bølling interstadial, ice retreated to the fjord entrances at Kejser Franz Joseph Fjord and Kong Oscar Fjord, and most probably into the fjord at Scoresby Sund. A subsequent readvance up to a mid-shelf position likely took place in the Younger Dryas. Thereafter, Holocene retreat on the shelf and in the outer fjord areas most likely was rapid, except for two phases of stabilization at the entrance of Kong Oscar Fjord. Apart from glacial landforms, the swath bathymetry data revealed a large amount of landslide debris in the southern part of Scoresby Sund. The origin of this debris is an up to 1500 m high mountain cliff that likely collapsed sometime in the Holocene. On first approximation, the debris volume is a magnitude larger than the volumes of more recent rock falls, which resulted in devastating tsunamis. The size of the debris, as well as the height of its source, suggests that one or multiple tsunamis most probably once hit the coasts of Scoresby Sund.

Description: Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic Water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here, we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation (MC) approach. A new 150-m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous datasets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals the total sea level potential of the Greenland Ice Sheet is 7.42±0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.

Description: During the last glacial maximum, 26,500-19,000 years before present, the entire Greenland Ice Sheet extended onto the continental shelf that today is covered by the ocean. However, its extent on the shelf is still not resolved. The bathymetry of the shelf reveals morphologic remnants that have been created by this extensive ice sheet. These remnants, also referred to as submarine glacial landforms, allow us to infer the extent of the past Greenland Ice Sheet as well as giving information of its ice stream pathways and its retreat behavior in the succession of the last ice age. In this thesis, data that have been acquired since the 1980s in the waters offshore Northeast Greenland have been investigated for submarine glacial landforms that are used to derive the setting of the past ice sheet system.