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New map reveals what lies beneath the Southern Ocean

An international team of researchers led by the Alfred Wegener Institute has created the most detailed seafloor map of the Southern Ocean to date. Climate, biodiversity, and ocean currents are all influenced by features on the ocean floor, which means the new map is critically important for research. 

“The Southern Ocean is a major component of the coupled ocean-atmosphere climate system and includes the largest ocean current on earth, the Antarctic Circumpolar Current (ACC). It is furthermore the most important ocean region for the uptake of anthropogenic CO2 and heat from the atmosphere, and cold and dense bottom waters form on the shelves surrounding Antarctica,” wrote the study authors.

“Interactions of the Southern Ocean with Antarctic glaciers and ice shelves are the main drivers of present, past, and future Antarctic ice sheet mass balance and thus global sea-level change. Biologically, the Southern Ocean is a high-productivity area with high biodiversity.”

“The Southern Ocean is also one of the most remote and harshest areas of the world with extensive sea-ice cover and year-round severe weather conditions.”

Few regions of the Southern Ocean seafloor have been surveyed and mapped in detail. The International Bathymetric Chart of the Southern Ocean (IBCSO) is an international project coordinated by the AWI.

“No matter where you travel or work, you need a map for orientation. That’s why virtually all oceanographic disciplines rely on detailed maps of the ocean floor,” explained Dr. Boris Dorschel-Herr. “For example, the seafloor topography of the Southern Ocean is essential to understanding a range of climate-relevant processes.”

“Warm water masses flow into deep troughs in the continental shelf towards the ice shelves and glaciers of the Antarctic, affecting how they melt. Conversely, the stability and calving behavior of glaciers and ice sheets greatly depend on the features of the ground beneath them. With the IBCSO v2, we have delivered the best and most detailed representation of the Southern Ocean to date.”

The first IBCSO high-resolution map of the area (IBCSO v1) was released in 2013. Since that time, a large amount of new measurement data has been collected. 

“The new version of IBCSO – IBCSO v2 – for the Southern Ocean now covers the entire area south of the 50th parallel – which means 2.4 times as much seafloor as the first version – at a high resolution of 500 by 500 meters,” explained Dr. Dorschel-Herr. 

“As a result, the Antarctic Circumpolar Current and the key oceanographic ‘gateways’ essential to understanding it – the Drake Passage and the Tasmanian Passage – are included in their entirety. The chart is based on more than 25.5 billion measurements supplied by 88 institutions in 22 countries.”

The high-resolution map of the Southern Ocean is available for download free of charge at the project website

The study is published in the Nature journal Scientific Data.

By Chrissy Sexton, Staff Writer

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