Wintertime <scp>ENSO</scp> influence on late spring European climate: the stratospheric response and the role of North Atlantic <scp>SST</scp>

Bulić, Ivana Herceg; Mezzina, Bianca; Kucharski, Fred; Ruggieri, Paolo; King, Martin P.

doi:10.1002/joc.4980

Cited by 27 publications

(13 citation statements)

References 68 publications

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“…This would agree with LP2015 who found these alternated periods in the signal of EN in Europe in a low-top model, i.e., without a well-resolved stratosphere. This is also consistent with Herceg-Bulic et al (2017) that showed that the persistence of wintertime ENSO signal in both the stratosphere and the North Atlantic is required to enable the delayed ENSO impact on Europe in spring, and Scaife et al (2017) and Knight et al (2017) that highlighted the importance of including tropical Atlantic influence on seasonal forecast to obtain a correct signal of ENSO on Europe. Secondly, analysis of seasonal averages for late winter must be taken with caution because it is a transition season in which different mechanisms might work in different months and the predominant one might mask the rest.…”

Section: Summary and Discussionsupporting

confidence: 89%

“…As a second step, the EN-induced polar stratospheric anomalies descend reaching the troposphere in late winter (e.g. : Manzini et al 2006) and inducing a negative NAO phase (Bell et al 2009;Cagnazzo and Manzini 2009;Ineson and Scaife 2009;Herceg-Bulic et al 2017). Most of these studies also showed that the occurrence of a major stratospheric warming (MSW) is essential for the establishment of the aforementioned downward propagation of the EN-induced stratospheric anomalies.…”

Section: Introductionmentioning

confidence: 99%

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Stratospheric role in interdecadal changes of El Niño impacts over Europe

et al. 2018

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The European precipitation response to El Niño (EN) has been found to present interdecadal changes, with alternated periods of important or negligible EN impact in late winter. These periods are associated with opposite phases of multi-decadal sea surface temperature (SST) variability, which modifies the tropospheric background and EN teleconnections. In addition, other studies have shown how SST anomalies in the equatorial Pacific, and in particular, the location of the largest anomalous SST, modulate the stratospheric response to EN. Nevertheless, the role of the stratosphere on the stationarity of EN response has not been investigated in detail so far. Using reanalysis data, we present a comprehensive study of EN teleconnections to Europe including the role of the ocean background and the stratosphere in the stationarity of the signal. The results reveal multidecadal variability in the location of EN-related SST anomalies that determines different teleconnections. In periods with relevant precipitation signal over Europe, the EN SST pattern resembles Eastern Pacific EN and the stratospheric pathway plays a key role in transmitting the signal to Europe in February, together with two tropospheric wavetrains that transmit the signal in February and April. Conversely, the stratospheric pathway is not detected in periods with a weak EN impact on European precipitation, corresponding to EN-related SST anomalies primarily located over the central Pacific. SST mean state and its associated atmospheric background control the location of EN-related SST anomalies in different periods and modulate the establishment of the aforementioned stratospheric pathway of EN teleconnection to Europe too.

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Section: Summary and Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Stratospheric role in interdecadal changes of El Niño impacts over Europe

et al. 2018

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“…The model has been used to investigate simple troposphere–stratosphere interactions and a discussion around the suitability of the model is provided by Herceg‐Bulic et al (2017), thus showing that it is capable of capturing some key features of the troposphere–stratosphere interaction, despite the low top. The transient eddy heat and momentum flux climatology of the model is presented in Figures S1 and S2 in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

The transient atmospheric response to a reduction of sea‐ice cover in the Barents and Kara Seas

Ruggieri

Kucharski

Buizza

et al. 2017

Quart J Royal Meteoro Soc

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The observed reduction of Arctic sea-ice has drawn a lot of interest for its potential impact on mid-latitude weather variability. One of the outstanding challenges is to achieve a deeper understanding of the dynamical processes involved in this mechanism.To progress in this area, we have designed and performed an experiment with an intermediate complexity atmospheric model. The experiment shows a transient atmospheric response to a surface diabatic heating in the Barents and Kara seas leading to an anomalous circulation first locally, then over the polar region and finally over the Euro-Atlantic sector. A hypothesis that explains the mechanisms for the propagation of the signal is put forward. The discussion of this hypothesis provides an insight into the nature of the link between sea-ice forcing and the modes of internal variability of the atmosphere. We demonstrate that after removal of sea ice in the Barents and Kara seas, first the linear atmospheric response dominates and is confined in the proximity of the heating area, then a large-scale response, associated also to eddy-feedback, is found and finally anomalies reach the lower-stratosphere and show a hemispheric pattern in the troposphere. These results identify the drivers of the tropospheric connection between sea-ice variability and the North Atlantic Oscillation and highlight the role of the lower stratosphere.

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“…Moron and Gouirand (), King et al (), and Ayarzagüena, Inseon, et al, () suggest that there exists a significantly different teleconnection of ENSO to the Europe/North Atlantic sector in November‐December versus January‐March. Herceg‐Bulić et al () find that the January‐March ENSO response over Europe is maintained by both the stratosphere and extratropical Atlantic SSTs. Jiménez‐Esteve and Domeisen () find that the tropospheric teleconnection across North America that yields a negative NAO for El Niño is present during January‐March, while the signal is limited to February for La Niña, modulated by decadal variability.…”

Section: Enso Teleconnections To the Stratospherementioning

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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Wintertime ENSO influence on late spring European climate: the stratospheric response and the role of North Atlantic SST

Cited by 27 publications

References 68 publications

Stratospheric role in interdecadal changes of El Niño impacts over Europe

Stratospheric role in interdecadal changes of El Niño impacts over Europe

The transient atmospheric response to a reduction of sea‐ice cover in the Barents and Kara Seas

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

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