How Do Tropical, Northern Hemispheric, and Southern Hemispheric Volcanic Eruptions Affect ENSO Under Different Initial Ocean Conditions?

• ©2018. American Geophysical Union. All Rights Reserved. Current understanding of volcanic effects on El Niño–Southern Oscillation in terms of eruption type and initial ocean condition (IOC) remains elusive. We use last-millennium proxy reconstructions to show how volcanic impacts depend on eruption type and IOC. When the IOC is not a strong El Niño, it is likely that an El Niño will mature in the second winter following 79% (p<0.01) of Northern Hemispheric eruptions and in the first winter following 81% (p<0.01) of tropical and 69% of Southern Hemispheric eruptions. For a strong El Niño-IOC, no significant El Niño will occur in the first winter after any type of eruption. The eruptions need to be large enough to cause these diverse effects. Our last-millennium simulation confirms the IOC effect, except that a La Niña occurs in the first winter following most tropical eruptions due to overestimated volcanic cooling in the model.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

ENSO

ENSO reconstruction

initial ocean condition

millennium simulation

volcanic cooling

volcano type

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