Advancing predictions of the Atlantic Niño and its oceanic drivers

The Atlantic Niño, a key climate pattern in the tropical Atlantic Ocean and the counterpart to the well-known El Niño in the Pacific Ocean, influences rainfall, hurricanes, and other climate and weather worldwide. Scientists recently identified two distinct variations of the Atlantic Niño phenomenon that arise under different conditions, but those mechanisms have been unclear. The Central Atlantic Niño is characterized by warm sea surface temperatures concentrated in the central equatorial Atlantic, while the Eastern Atlantic Niño features warming in the eastern equatorial Atlantic, near the West African coast. A new study published in npj Climate and Atmospheric Science used past ocean and climate data, like ocean currents and wind, with computer models to understand how each type of Atlantic Niño forms. The researchers, including Antonietta Capotondi of NOAA’s Physical Sciences Laboratory, found that the Central Atlantic Niño forms when the subtropical waters in the South Atlantic undergo warming. The results show that the Eastern Atlantic Niño is triggered by ocean Kelvin waves, which move across the Atlantic and push warm water deeper below the surface, allowing a build-up of heat near the coast of West Africa.