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On the role of ozone feedback in the ENSO amplitude response under global warming

Accepted version
Peer-reviewed

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Authors

Nowack, PJ 
Braesicke, P 
Abraham, NL 
Pyle, JA 

Abstract

The El Niño Southern Oscillation (ENSO) in the tropical Pacific Ocean is of key importance to global climate and weather. However, state-of-the-art climate models still disagree on the ENSO's response under climate change. The potential role of atmospheric ozone changes in this context has not been explored before. Here, we show that differences between typical model representations of ozone can have a first-order impact on ENSO amplitude projections in climate sensitivity simulations. The vertical temperature gradient of the tropical middle-to-upper troposphere adjusts to ozone changes in the upper troposphere and lower stratosphere, modifying the Walker circulation and consequently tropical Pacific surface temperature gradients. We show that neglecting ozone changes thus results in a significant increase in the number of extreme ENSO events in our model. Climate modeling studies of the ENSO often neglect changes in ozone. We therefore highlight the need to understand better the coupling between ozone, the tropospheric circulation and climate variability.

Description

Keywords

ozone, climate change, ENSO, Walker circulation, global warming, climate variability

Journal Title

Geophysical Research Letters

Conference Name

Journal ISSN

0094-8276
1944-8007

Volume Title

44

Publisher

American Geophysical Union
Sponsorship
European Research Council (267760)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8H12/83/009)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8/H12/83/003)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8/H12/83/003)
National Centre for Atmospheric Science (NERC) (via University of Leeds) (R8/H12/83/003)
European Research Council. Grant Number: 267760 European Research Council. Grant Number: 267760 Natural Environment Research Council (NERC). Grant Number: RH/H10/19 Natural Environment Research Council (NERC). Grant Number: R8/H12/124 National Centre for Atmospheric Science (NCAS) Helmholtz-Gemeinschaft (HGF)