It is the dominant mode of year-to-year variability that results in alternating warming and cooling episodes of sea surface temperatures accompanied by changes in atmospheric circulation.
[1] The term Atlantic Niño comes from its close similarity with the El Niño-Southern Oscillation (ENSO) that dominates the tropical Pacific basin.
[4] The equatorial warming and cooling events associated with the Atlantic Niño are known to be strongly related to rainfall variability over the surrounding continents, especially in West African countries bordering the Gulf of Guinea.
This phenomenon results from air-sea interaction, producing a coupled atmosphere-ocean system that oscillates with periods on the order of three to five years.
However, the physical basis for this oscillation is not limited strictly to the Pacific basin, and indeed, a very similar mode of variability exists in the equatorial Atlantic, albeit on a smaller scale.
This is strikingly similar to the wind stress anomalies seen in the Pacific during El Niño (or La Niña) events, although centered farther west in the Atlantic basin.
[5] While the spatial characteristics of the mature Atlantic Niño are quite similar to its Pacific counterpart, its temporal variability is somewhat different.
[7] In fact, the ability to predict the Atlantic Niño is a major research question given its impact on seasonal climate.
In particular, the persistent and late-onset varieties are characterized by strong equatorial Atlantic sea surface temperature anomalies that remain until the end of the year.
In comparison, the early-terminating and early-onset varieties are linked to a limited period of increased rainfall over the West Africa sub-Sahel region (July - August).