International Bathymetric Chart of the Southern Ocean (IBCSO) Expert Group

About

In 2000, member states of the International Hydrographic Organization (IHO) decided to delimit the waters within the Antarctic Convergence as a fifth ocean - the Southern Ocean - by combining the southern portions of the Atlantic Ocean, Indian Ocean, and Pacific Ocean.

The sea floor topography of the Southern Ocean is largely unknown or predicted. Survey activities of modern icebreaking vessels during the last decade using multibeam and other systems have increased the data availability, making it possible for compilations of new bathymetric charts around Antarctica.

Transition from analogue IBCs of the 1980s to digital methods started in 1997 with the northern equivalent of the International Bathymetric Chart of the Southern Ocean (IBCSO), the International Bathymetric Chart of the Arctic Ocean (IBCAO). Following the success of the IBCAO, the IBCSO was initiated in 2006. The objective of the IBCSO program is the design and implementation of an enhanced digital database that contains bathymetric data available south of 60S latitude. Based on this data container a consistent bathymetric chart of the Southern Ocean is designed.

The IBCSO program is endorsed by international organizations such as the Intergovernmental Oceanographic Commission (IOC) of UNESCO, the International Hydrographic Organization (IHO), and the Scientific Committee on Antarctic Research (SCAR).

The significance of the sea floor topography is reflected by the full spectrum of applications in the fields of:

The Sea Floor in Geosciences

Bathymetry is the first key to geo-related seabed processes - tectonic and igneous activities as well as marine sedimentation. The sea floor topography is mainly caused by endogenic processes related to plate tectonics and sea floor spreading, resulting in the geomorphology of the oceanic seabed. The shape and the depth of the sea floor provide information about:

  • delimitation of the ocean-continent boundary
  • crustal heterogeneities and variations in geophysical anomalies
  • crustal behaviour - seismicity - with regards to faults, earthquakes and landslides
  • depth and shape as important input parameters in Tsunami Warning Systems


The Sea Floor in Physical Sciences

Bathymetry primarily influences ocean circulation. Unfortunately, the bathymetry is only poorly known in polar regions. Limited access, severe climate conditions and vast sea-ice coverage hamper the continuous data acquisition around the Antarctic continent. Poor knowledge of the bathymetry is the limiting factor for new progress in ocean models. Interactions of bathymetry with oceanography include:

  • topographic steering of ocean flows
  • transport and mixing of water through ocean gateways
  • ocean models are sensitive to bathymetry.
  • improvement of ocean models by accurate bathymetry


The Sea Floor in Life Sciences

The transformation of multibeam data into classified products for coastal and marine research supports protection and conservation of marine biodiversity. Bathymetric data provide additional numerical descriptors of terrain variables. Due to the high correlation of topographic features with ecological niches, the knowledge about benthic habitats is of great importance for:

  • multi-scale terrain analysis
  • predictive habitat modeling (Bathymetric Position Index - BPI)
  • characterization of habitats (Terrain Ruggedness Index - TRI)
  • description of marine ecosystems (Benthic Terrain Modeler - BTM)

 

The Sea Floor in Observing Systems

The IBCSO may give impetus on programs like the Southern Ocean Observing System (SOOS) in consideration of:

  • important ocean model input parameter (e.g. depth, slope, orientation, BIP, TRI)
  • improvement of state-of-the-art ocean models
  • interactions and coupling of system domains (air, water, ice, rocks, life)
  • essential system variables in observing systems
  • and implementation of international and interdisciplinary research