PLANET EARTH
Scientists have discovered a previously undetected water mass 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 West Africa. The water mass, named the Atlantic Equatorial Water, forms along the equator as ocean currents mix separate bodies of water to the north and south. Until the Atlantic Equatorial Water’s discovery, scientists had spotted waters mixing along the equator in the Pacific and Indian oceans, but never in the Atlantic. “It seemed controversial that the equatorial water mass is present in the Pacific and Indian oceans but missing in the Atlantic Ocean because the equatorial circulation and mixing in all three oceans have common features,” said Viktor Zhurbas, a physicist and oceanologist at the Shirshov Institute of Oceanology in Moscow.
“The identified new water mass has allowed us to complete, or at least more accurately describe, the phenomenological pattern of basic water masses of the world ocean.”
Far from being the same everywhere, ocean water is a vast patchwork of interconnected masses and layers, mixed together and split apart again by currents, eddies and changes to temperature and salinity. Water masses are the distinct parts of this motley arrangement; each body of water has a shared geography, formation history and common physical properties, such as density and dissolved isotopes of oxygen, nitrate and phosphate. To distinguish water masses, oceanographers chart the relationship between temperature and salinity across the ocean, two measurements that combine to determine the density of seawater. In 1942 this charting led to the discovery of equatorial waters in the Pacific and Indian oceans. Fo
