Atlantic Niño is the Atlantic counterpart of El Niño in the Pacific, often referred to as El Niño’s little brother. It was previously thought to have only regional influence on rainfall variability in West Africa, but a growing number of studies have shown that Atlantic Niño also plays an important role in the development of El Niño–Southern Oscillation, as well as in the formation of powerful hurricanes near the coast of West Africa. In a study published in Geophysical Research Letters, Lee et al. (2023) investigated the development of an extreme Atlantic Niño in the summer of 2021. The study showed that the 2021 event was preconditioned by warm waters piled up near the South American coast, and then directly triggered by a westerly wind burst event that drove the warm waters eastward. The westerly wind burst event was driven by a patch of tropical thunderstorms that formed across the Indian Ocean and moved slowly eastward across the Pacific, South America, and the Atlantic, also known as the Madden-Julian Oscillation (MJO). Westerly wind bursts driven by the Madden-Julian Oscillation are fundamental for the development of El Niño in the Pacific, but a previously unidentified driver for Atlantic Niño, and thus may improve our ability to predict future Atlantic Niño events.
Figure 1 from Lee et al. (2023). (a) Time series of June–August averaged SSTAs in the eastern equatorial region (20°W–0°, 3°S–3°N; ATL3). (b) Time-longitude plot of equatorial Atlantic SSTAs, averaged between 3°S and 3°N, from January to December 2021. (c) Tropical Atlantic SST (shades), SSH (contours) and 10-m wind (vectors) anomalies, and (d) precipitation anomalies during June-August 2021. Positive and negative SSHAs are indicated by green and cyan contour lines, respectively in (c). The ATL3 region is indicated in (d). The units for SST, SSH, 10-m wind, and precipitation are in °C, cm, m s−1, and mm day-1, respectively. The contour interval for SSH anomalies is 2.0 cm.
Lee, S.-K., Lopez, H., Tuchen, F. P., Kim, D., Foltz, G. R., & Wittenberg, A. T. (2023). On the genesis of the 2021 Atlantic Niño. Geophysical Research Letters, 50, e2023GL104452. https://doi.org/10.1029/2023GL104452
Ocean to Climate 
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