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

Nowack, Peer; Braesicke, Peter; Abraham, N. L.; Pyle, J. A.

doi:10.1002/2016gl072418

Cited by 36 publications

(37 citation statements)

References 64 publications

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“…Here we explore how considering or (to some extent) neglecting ozone changes under climate change alters the climate sensitivity of a fully interactive atmosphere-ocean coupled climate model. Our work stands in context with a number of recent studies that have confirmed that the representation of ozone in state-of-the-art climate models can affect tropospheric and surface climate change projections (e.g., Chiodo & Polvani, 2016a, 2016bDietmüller et al, 2014;Muthers et al, 2014Muthers et al, , 2016Noda et al, 2017;Nowack et al, 2015Nowack et al, , 2017Son et al, 2008). It is further motivated by the apparently strong model and scenario dependency of climate impacts associated with changes in ozone.…”

Section: Introductionmentioning

confidence: 67%

The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

et al. 2018

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A number of climate modeling studies have shown that differences between typical choices for representing ozone can affect climate change projections. Here we investigate potential climate impacts of a specific ozone representation used in simulations of the Hadley Centre Global Environment Model for the Coupled Model Intercomparison Project Phase 5. The method considers ozone changes only in the troposphere and lower stratosphere and prescribes stratospheric ozone elsewhere. For a standard climate sensitivity simulation, we find that this method leads to significantly increased global warming and specific patterns of regional surface warming compared with a fully interactive atmospheric chemistry setup. We explain this mainly by the suppressed part of the stratospheric ozone changes and the associated alteration of the stratospheric water vapor feedback. This combined effect is modulated by simultaneous cirrus cloud changes. We underline the need to understand better how representations of ozone can affect climate modeling results and, in particular, global and regional climate sensitivity estimates.

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Section: Introductionmentioning

confidence: 67%

The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

et al. 2018

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“…Many studies have highlighted that the representation of ozone can impact the results of such climate sensitivity simulations. The use of non-adaptive ozone climatologies in abrupt 4xCO 2 simulations can affect climate sensitivity estimates (Li et al 2013, Muthers et al 2014, Dietmüller et al 2014, Nowack et al 2015, 2018, the position of the jet streams Polvani 2017, Nowack et al 2018) as well as the response of the Walker circulation and ENSO (Nowack et al 2017). Similar effects have been found for paleo-climates and solar forcing scenarios (Haigh 1996, Heinemann 2009, Chiodo and Polvani 2016, Muthers et al 2016, Noda et al 2017.…”

Section: Introductionmentioning

confidence: 75%

Using machine learning to build temperature-based ozone parameterizations for climate sensitivity simulations

Nowack

Braesicke

Haigh

et al. 2018

Environ. Res. Lett.

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A number of studies have demonstrated the importance of ozone in climate change simulations, for example concerning global warming projections and atmospheric dynamics. However, fully interactive atmospheric chemistry schemes needed for calculating changes in ozone are computationally expensive. Climate modelers therefore often use climatological ozone fields, which are typically neither consistent with the actual climate state simulated by each model nor with the specific climate change scenario. This limitation applies in particular to standard modeling experiments such as preindustrial control or abrupt 4xCO 2 climate sensitivity simulations. Here we suggest a novel method using a simple linear machine learning regression algorithm to predict ozone distributions for preindustrial and abrupt 4xCO 2 simulations. Using the atmospheric temperature field as the only input, the regression reliably predicts three-dimensional ozone distributions at monthly to daily time intervals. In particular, the representation of stratospheric ozone variability is much improved compared with a fixed climatology, which is important for interactions with dynamical phenomena such as the polar vortices and the Quasi-Biennial Oscillation. Our method requires training data covering only a fraction of the usual length of simulations and thus promises to be an important stepping stone towards a range of new computationally efficient methods to consider ozone changes in long climate simulations. We highlight key development steps to further improve and extend the scope of machine learning-based ozone parameterizations.

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“…It has been suggested that enhanced (reduced) Arctic ozone in March preferentially leads to a La Niña (El Niño) event, 20 months later (Garfinkel, ; F. Xie et al, ). Nowack et al () suggest based on a modeling study that neglecting possible future changes in the vertical structure of tropical ozone might be one of the reasons for the simulated higher frequency of extreme ENSO events. Enhanced solar variability may also affect ENSO, though the robustness of this connection is difficult to establish (Haam & Tung, ; Roy & Haigh, ).…”

Section: Factors Influencing Enso Teleconnectionsmentioning

confidence: 99%

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

Domeisen

Garfinkel²,

Butler

2019

Reviews of Geophysics

316

284

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El Niño and La Niña events in the tropical Pacific have significant and disrupting impacts on the global atmospheric and oceanic circulation. El Niño Southern Oscillation (ENSO) impacts also extend above the troposphere, affecting the strength and variability of the stratospheric polar vortex in the high latitudes of both hemispheres, as well as the composition and circulation of the tropical stratosphere. El Niño events are associated with a warming and weakening of the polar vortex in the polar stratosphere of both hemispheres, while a cooling can be observed in the tropical lower stratosphere. These impacts are linked by a strengthened Brewer-Dobson circulation. Anomalous upward wave propagation is observed in the extratropics of both hemispheres. For La Niña, these anomalies are often opposite. The stratosphere in turn affects surface weather and climate over large areas of the globe. Since these surface impacts are long-lived, the changes in the stratosphere can lead to improved surface predictions on time scales of weeks to months. Over the past decade, our understanding of the mechanisms through which ENSO can drive impacts remote from the tropical Pacific has improved. This study reviews the possible mechanisms connecting ENSO to the stratosphere in the tropics and the extratropics of both hemispheres while also considering open questions, including nonlinearities in the teleconnections, the role of ENSO diversity, and the impacts of climate change and variability.Plain Language Summary El Niño and La Niña events, the irregular warming and cooling of the tropical Pacific that occurs every couple of years, have disrupting impacts spanning the entire world. These remote impacts, so-called "teleconnections", also reach the stratosphere, the layer of the atmosphere starting at around 10 km above the Earth's surface. El Niño leads to a warming of the stratosphere in both hemispheres, while the lower tropical stratosphere cools. These signatures are linked by a strengthened stratospheric circulation from the tropics to the polar regions. El Niño also leads to more frequent breakdowns of the stratospheric polar vortex, a band of strong eastward winds in the polar stratosphere. For La Niña, these effects tend to be opposite, though they are not always robust, suggesting nonlinear or nonstationary effects, long-term variability, and trends in the teleconnections. The observational data record is not yet long enough to make conclusions with certainty, and models that try to reproduce the teleconnections indicate that teleconnections might be more linear than the limited number of observations indicate. Further research will be needed to separate the El Niño and La Niña teleconnections from other effects and to determine to what extent nonlinearity and nonstationarity are indeed present.

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

Cited by 36 publications

References 64 publications

The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

Using machine learning to build temperature-based ozone parameterizations for climate sensitivity simulations

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

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