Scientists have discovered a previously undetectable body of water in the middle of the Atlantic Ocean: a gigantic body of water stretching across the Atlantic from the tip of Brazil to the Gulf of Guinea, near the ‘West Africa.
The body of water, called Atlantic equatorial water, forms along the equator when ocean currents mix distinct bodies of water to the north and south.
Until the discovery of Atlantic equatorial water, scientists had spotted waters mixing along the equator in the Pacific and Indian Oceans, but never in the Atlantic. The researchers published their results on October 28 in the journal Geophysical research letters.
Related: Weakening of the Gulf Stream is now 99% certain and the ramifications will be global
“It seems controversial that the equatorial water mass is present in the Pacific and Indian Oceans but absent in the Atlantic Ocean, because equatorial circulation and mixing in all three oceans have common features,” Victor Jourbas, a physicist and oceanologist at the Shirshov Institute of Oceanology in Moscow, told Live Science in an email. “The newly identified water mass allowed us to complete (or at least more precisely describe) the phenomenological model of the basic water masses of the World Ocean.”
Far from being the same everywhere, ocean water is a vast mosaic of interconnected masses and layers, mixed and divided again by currents, eddies, and changes in temperature and salinity.
The water masses are the distinct parts of this motley arrangement; Each body of water has common geography, formation history, and physical properties, such as density and dissolved isotopes of oxygen, nitrate, and phosphate.
To distinguish between water masses, oceanographers plot the relationship between temperature and salinity across the ocean – two measurements that combine to determine the density of seawater.
In 1942, this temperature-salinity mapping led to the discovery of the equatorial waters of the Pacific and Indian Oceans. Formed by the mixing of waters to the north and south, the equatorial waters of India and the Pacific have temperatures and salinities curved along lines of constant density that are easily distinguished from the surrounding water. However, no such relationship could be observed in the Atlantic.
To search for the missing body of water, scientists combed through data collected by the Argo program, an international network of self-submerged robotic floats scattered across the world’s oceans.
After analyzing the data collected by this floating network, the researchers spotted an unnoticed temperature-salinity curve, nestled parallel to the curves demarcating the central waters of the North Atlantic and the South Atlantic to the north and south: the equatorial waters of the Atlantic.
“It was easy to confuse the equatorial waters of the Atlantic with the central waters of the South Atlantic, and to distinguish them it was necessary to have a fairly dense network of vertical temperature and salinity profiles covering the entire Atlantic Ocean,” Zhurbas explained.
Now that the water mass has been identified, it will allow scientists to better understand ocean mixing processes, which are essential for the transport of heat, oxygen and nutrients by oceans across the world, a Zhurbas said.