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New moorings for better data on the South Atlantic Ocean

Two full-depth moorings have been deployed to enhance our knowledge of South Atlantic currents and ecosystems.

Climate Change and Environment icon Climate Change and Environment

Two new full-depth, instrumented moorings have been deployed off the eastern coast of South America as part of an international effort to gain more insight into the currents and ecosystems in a data-sparse region of the South Atlantic Ocean. Put into use by the EU-funded projects iAtlantic and TRIATLAS, the scientific moorings are helping to achieve the goals outlined in the Belem Statement, a joint declaration on Atlantic Ocean research between the EU, Brazil and South Africa. They are also contributing to the fulfilment of bilateral agreements between the EU and other countries. The moorings will measure variations in the Atlantic Meridional Overturning Circulation (AMOC), a system of ocean currents that circulates water within the Atlantic Ocean, bringing warm water north and cold water south. Consisting of a northward upper-ocean flow compensated by a southward deep-ocean flow, the AMOC is the main engine driving our planet’s climate system, and it affects not only ocean life but also the weather and economy of coastal nations.

Warmer planet, weaker system

As reported in a press release posted on the TRIATLAS website, the “upper AMOC cell is connected to deep-water formation and sinking in the subpolar North Atlantic and upwelling in the Southern Ocean. Beneath the upper cell is a weaker abyssal cell, sourced by the sinking of dense water near Antarctica.” However, global warming is suspected to be weakening the system. In addition, natural variations may also occur, caused by reduced sinking water in the north and changes in the water mass exchange in the south. “The South Atlantic is particularly important,” states Prof. Peter Brandt of iAtlantic and TRIATLAS project partner GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany. “Changes in the AMOC that result from water mass exchanges between the Atlantic and the Indian and Pacific oceans, can best be detected in the south, and then compared to changes originating in the well-observed North Atlantic,” he explains. Dr María Paz Chidichimo of iAtlantic project partner National Scientific and Technical Research Council, Argentina, adds: “The South Atlantic is the only ocean basin with a net equatorward heat transport, and where freshwater transports may be key to AMOC stability. It is also the basin where the upper and abyssal overturning cells of the AMOC are both important.” The new moorings contribute to the South Atlantic Meridional Overturning Circulation – Basin-wide Array, a measurement array along 34.5 degrees south on both sides of the Atlantic. Extending the knowledge provided by current south-western Atlantic measurements using echosounders on the seabed, the two moorings will directly measure seawater properties from the seabed up to the surface. The goal facilitated by iAtlantic (Integrated Assessment of Atlantic Marine Ecosystems in Space and Time) and TRIATLAS (Tropical and South Atlantic climate-based marine ecosystem predictions for sustainable management) is to measure changes in climate through the coming decades. “We are proud to contribute to the long-term efforts to maintain and develop the global observing system,” remarks Prof. Brandt. For more information, please see: iAtlantic project website TRIATLAS project website

Keywords

iAtlantic, TRIATLAS, ocean, water, South Atlantic, mooring, current, marine ecosystem

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