Tropical explosive volcanic eruptions can trigger El Niño by cooling tropical Africa

Khodri, M., Izumo, T., Vialard, J., Janicot, S., Cassou, C., Lengaigne, M., Mignot, J., Gastineau, G., Guilyardi, E. ORCID: https://orcid.org/0000-0002-2255-8625, Lebas, N., Robock, A. and McPhaden, M. J. (2017) Tropical explosive volcanic eruptions can trigger El Niño by cooling tropical Africa. Nature Communications, 8 (1). 778. ISSN 2041-1723 doi: 10.1038/s41467-017-00755-6

Abstract/Summary

Stratospheric aerosols from large tropical explosive volcanic eruptions backscatter shortwave radiation and reduce the global mean surface temperature. Observations suggest that they also favour an El Niño within 2 years following the eruption. Modelling studies have, however, so far reached no consensus on either the sign or physical mechanism of El Niño response to volcanism. Here we show that an El Niño tends to peak during the year following large eruptions in simulations of the Fifth Coupled Model Intercomparison Project (CMIP5). Targeted climate model simulations further emphasize that Pinatubo-like eruptions tend to shorten La Niñas, lengthen El Niños and induce anomalous warming when occurring during neutral states. Volcanically induced cooling in tropical Africa weakens the West African monsoon, and the resulting atmospheric Kelvin wave drives equatorial westerly wind anomalies over the western Pacific. This wind anomaly is further amplified by air-sea interactions in the Pacific, favouring an El Niño-like response.El Niño tends to follow 2 years after volcanic eruptions, but the physical mechanism behind this phenomenon is unclear. Here the authors use model simulations to show that a Pinatubo-like eruption cools tropical Africa and drives westerly wind anomalies in the Pacific favouring an El Niño response.

Additional Information	** From PubMed via Jisc Publications Router. ** History: ** received: 25-05-2016 ** accepted: 21-07-2017
Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/73162
Identification Number/DOI	10.1038/s41467-017-00755-6
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Additional Information	** From PubMed via Jisc Publications Router. ** History: ** received: 25-05-2016 ** accepted: 21-07-2017
Publisher	Nature Publishing Group
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