Nonstationarity of the link between the Tropics and the summer East Atlantic pattern

Rieke, Ole; Greatbatch, Richard John; Gollan, Gereon

doi:10.1002/asl.1026

Cited by 7 publications

(5 citation statements)

References 29 publications

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“…Similar to the TNA SSTAs, the neighboring Caribbean region also plays a role in the excitation and propagation of Rossby waves to the extratropics (Wulff et al, 2017;Hardiman et al, 2019;Neddermann et al, 2019;Rieke et al, 2021). In particular, Rossby wave trains originating in the Caribbean region can influence the summer East Atlantic (SEA) pattern, which is related to European summer climate (Wulff et al, 2017).…”

Section: Introductionmentioning

confidence: 98%

“…The complexity present in the ENSO impact over Europe results in part from several ENSO teleconnections that propagate through different geographical regions, as well as different atmospheric levels (Rodríguez-Fonseca et al, 2016). For example, teleconnections can propagate through the extratropical troposphere (Bulić and Kucharski, 2012;Jiménez-Esteve and Domeisen, 2018;Mezzina et al, 2020), the extratropical stratosphere (Butler et al, 2014;Ayarzagüena et al, 2018;Domeisen et al, 2019), or the Caribbean region (Wulff et al, 2017;Hardiman et al, 2019;Rieke et al, 2021). Furthermore, the ENSO teleconnection can be modulated by different regions and processes along its way, such as the tropical North Atlantic (Sung et al, 2013;Casselman et al, 2021) and the Indian Ocean (Zhong et al, 2005;Fletcher and Cassou, 2015;Joshi et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Modulation of the El Niño teleconnection to the North Atlantic by the tropical North Atlantic during boreal spring and summer

Casselman

Jiménez‐Esteve

Domeisen

2022

Weather Clim. Dynam.

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Abstract. Equatorial Pacific sea surface temperature anomalies (SSTAs) associated with El Niño–Southern Oscillation (ENSO) can influence the North Atlantic European (NAE) region. ENSO tends to be negatively correlated with the North Atlantic Oscillation in winter, while this connection is less clear in boreal spring and summer when the ENSO teleconnection encounters altered background conditions (i.e., a weaker subtropical jet), which can modulate the signal on the way to the NAE region. One such region that modulates the ENSO teleconnection to the NAE region is the tropical North Atlantic (TNA). While several mechanisms exist for this modulation, we center our analysis on the Caribbean region and the Walker cells. In order to isolate the relevant mechanism, we force an idealized atmospheric circulation model with three different seasonally varying sea surface temperature patterns that represent an ENSO event with or without the influence of the TNA, focusing on the decaying phase of ENSO in boreal spring and summer. We find that in boreal spring, the TNA modulates the ENSO teleconnection to the NAE primarily through a propagating Rossby wave train, while in summer, the TNA's influence tends to strengthen the ENSO influence over the NAE sector. Overall, this study offers a deeper understanding of the inter-basin interactions through the Walker cell following an ENSO event and the central role of tropical Atlantic SSTAs in modulating the teleconnection to the NAE region in boreal spring and summer.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Modulation of the El Niño teleconnection to the North Atlantic by the tropical North Atlantic during boreal spring and summer

Casselman

Jiménez‐Esteve

Domeisen

2022

Weather Clim. Dynam.

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“…2019; Rieke et al, 2021). Furthermore, different regions modulate the regional response to ENSO teleconnections, such as the tropical North Atlantic (Sung et al, 2013;Casselman et al, 2021), and the Indian Ocean (Zhong et al, 2005;Fletcher and Cassou, 2015;Joshi et al, 2021).…”

mentioning

confidence: 99%

“…Furthermore, different regions modulate the regional response to ENSO teleconnections, such as the tropical North Atlantic (Sung et al, 2013;Casselman et al, 2021), and the Indian Ocean (Zhong et al, 2005;Fletcher and Cassou, 2015;Joshi et al, 2021). The teleconnections are, furthermore, sensitive to aspects such as the longitudinal position of Pacific sea surface temperatures (SSTs) (Zhang et al, 2019), non-stationarity (Rieke et al, 2021), and trends over time (Garfinkel et al, 2019).…”

mentioning

confidence: 99%

“…The neighbouring Caribbean region also plays a role in the excitation and propagation of Rossby waves to the extratropics (Wulff et al, 2017;Hardiman et al, 2019;Neddermann et al, 2019;Rieke et al, 2021). In particular, Rossby wave trains originating in the Caribbean region can influence the Summer East Atlantic (SEA) pattern, impacting European summer climate (Wulff et al, 2017).…”

mentioning

confidence: 99%

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Modulation of the ENSO teleconnection to the North Atlantic by the tropical North Atlantic and Caribbean

Casselman¹,

Jiménez‐Esteve²,

Domeisen³

2022

Preprint

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Abstract. El Niño Southern Oscillation (ENSO) can bring about inter-basin interactions, whereby Pacific sea surface temperature anomalies (SSTAs) may influence the North Atlantic European (NAE) region. However, ENSO's overall influence on the NAE remains unclear. One potential reason for this uncertainty may arise due to the region being dominated by several different mechanisms. Here we focus on one potential region, namely the Tropical North Atlantic (TNA), and determine how the SSTAs modulate the ENSO teleconnection towards the NAE region. As numerous pathways from the TNA may exist for this modulation, we further center our analysis onto the Caribbean region and Walker cells. We force an idealized atmospheric circulation model with three different seasonally varying sea surface temperature patterns that represent an ENSO event with or without the influence of the Atlantic. Our results demonstrate that modulation of the NAE region by the TNA SSTA and Caribbean region occurs in the boreal spring and summer following an ENSO event. In boreal spring, this modulation is primarily through a propagating Rossy wave train, while in the summer, the TNA's influence is nonlinear and tends to strengthen the ENSO influence over the NAE sector. Overall, this study offers a deeper understanding of the inter-basin interactions of the Walker cell following an ENSO event and the central role of tropical Atlantic SSTAs in modulating the teleconnection to the NAE region.

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Drivers of the ECMWF SEAS5 seasonal forecast for the hot and dry European summer of 2022

Patterson,

Befort,

O'Reilly

et al. 2024

Quart J Royal Meteoro Soc

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The European summer (June–August) 2022 was characterised by warm and dry anomalies across much of the continent, likely influenced by a northward‐shifted jet stream. These general features were well predicted by European Centre for Medium‐Range Weather Forecasts' system 5 seasonal forecast, initialised on May 1. Such successful predictions for European summers are relatively uncommon, particularly for atmospheric circulation. In this study, a set of hindcast experiments is employed to investigate the role that initialisation of the ocean, atmosphere, and land surface played in the 2022 forecast. We find that the trend from external forcing was the strongest contributor to the forecast near‐surface temperature anomalies, with atmospheric circulation and land‐surface interactions playing a secondary role. On the other hand, atmospheric circulation made a strong contribution to precipitation anomalies. Modelled Euro‐Atlantic circulation anomalies in 2022 were consistent with a La Niña‐forced teleconnection from the tropical Pacific. However, a northward jet trend in the model hindcasts with increasing greenhouse gas concentrations also contributed to the predicted circulation anomalies in 2022. In contrast, the observed linear trend in the jet over the past four decades was a southward shift, though it is unclear whether this trend was driven by external forcings or natural variability. Nevertheless, this case study demonstrates that important features of at least some European summers are predictable at the seasonal time‐scale.

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Nonstationarity of the link between the Tropics and the summer East Atlantic pattern

Cited by 7 publications

References 29 publications

Modulation of the El Niño teleconnection to the North Atlantic by the tropical North Atlantic during boreal spring and summer

Modulation of the El Niño teleconnection to the North Atlantic by the tropical North Atlantic during boreal spring and summer

Modulation of the ENSO teleconnection to the North Atlantic by the tropical North Atlantic and Caribbean

Drivers of the ECMWF SEAS5 seasonal forecast for the hot and dry European summer of 2022

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