Antarctic Seafloor Now Mapped in Unprecedented Detail

A digital map of the entire Antarctic seafloor has been created for the first time by an international team of scientists under the leadership of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Germany. This kind of reliable information on the depth and floor structure of the Southern Ocean has so far been available for only few coastal regions of the Antarctic.

The International Bathymetric Chart of the Southern Ocean (IBCSO) now shows the detailed topography of the seafloor for the entire area south of 60*S. An article presented to the scientific world by IBCSO has now appeared online in the scientific journal Geophysical Research Letters. The IBCSO data grid and the corresponding Antarctic chart will soon be freely available in the internet and are intended to help scientists amongst others to better understand and predict sea currents, geological processes or the behaviour of marine life.

The new bathymetric chart of the Southern Ocean is an excellent example of what scientists can achieve if researchers from around the world work across borders. "For our IBCSO data grid, scientists from 15 countries and over 30 research institutions brought together their bathymetric data from nautical expeditions. We were ultimately able to work with a data set comprising some 4.2 billion individual values", explains IBCSO editor Jan Erik Arndt, bathymetric expert at the Alfred Wegener Institute in Bremerhaven.

Collecting bathymetric data, as with the German research vessel Polarstern with its multibeam echo sounding system, was nowhere near enough, however, to develop a useful, three-dimensional model of the seafloor: "The ocean south of the 60th parallel extends over an area of some 21 million square kilometres and is therefore around 60 times as large as the Federal Republic of Germany. Reliable bathymetric data have so far existed for only 17 per cent of this area. The largest data gaps, for example, are in the deep sea regions of the south Indian Ocean and the South Pacific and in areas which experience difficult sea ice conditions throughout the year in some places, such as in the Weddell Sea", says Jan Erik Arndt.

For this reason the mappers did not just take the trouble to digitize old Antarctic nautical charts and to convert satellite data. They also used a mathematical trick by interpolating the data set.

Using this degree of detail IBCSO is primarily intended to push ahead with research: "The depth data of the Southern Ocean are of great interest to polar researchers from many disciplines. The 3D data grids of the seafloor enable oceanographers to model currents and the movement of the deep Antarctic water which is of such great importance.", explains Jan Erik Arndt.

However, despite the elation about the new model and its chart, it should not be forgotten that more than 80 per cent of the area of the South Polar Sea is still unchartered. Jan Erik Arndt: "We hope that as our data grid becomes better known in the scientific world, other scientists will be more willing to provide us with their data of current and future depth measurements in the South Polar Sea. The chances are not bad. A few new research ice breakers are currently being built around the world and every one of them will presumably be equipped with a modern multibeam echo sounder in the same way as Polarstern."

Both the IBCSO data grid and a digital print template of the chart (dimensions: 100 centimetres times 120 centimetres) will be available for downloading to everyone soon on the project website at  www.ibcso.org.