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

Linking tropical Africa cooling to El Niño onset In ATM, the equatorial Pacific wind stress and SST response is negative but hardly significant at the end of the eruption year (Fig. 5a, b yellow curve ), indicating that in isolation from the surface cooling, the direct effect of the radiative forcing on the atmosphere cannot explain the volcanically induced western Pacific initial westerly wind anomaly (Fig. 4e, f ) and the subsequent El Niño.

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