Abrupt and persistent atmospheric circulation changes in the North Atlantic under La Niña conditions

Several recent studies have linked the exceptional North Atlantic and Eurasian atmospheric evolution during late February and March 2018 to the Sudden Stratospheric Warming (SSW) that took place a few weeks earlier. February 2018 was characterized by an abrupt transition from the positive to the neg...

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Bibliographic Details
Published in:Weather and Climate Extremes
Main Authors: Marina García-Burgos, Iñigo Gómara, Belén Rodríguez-Fonseca, Juan Jesús González-Alemán, Pablo Zurita-Gotor, Blanca Ayarzagüena
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2023
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Online Access:https://doi.org/10.1016/j.wace.2023.100609
https://doaj.org/article/f456f18adcf144b6a3bc707e3d8fa85b
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Summary:Several recent studies have linked the exceptional North Atlantic and Eurasian atmospheric evolution during late February and March 2018 to the Sudden Stratospheric Warming (SSW) that took place a few weeks earlier. February 2018 was characterized by an abrupt transition from the positive to the negative phase of the North Atlantic Oscillation (NAO) and a subsequent persistence of the negative NAO for several weeks. This paper investigates the contribution of atmospheric and oceanic phenomena to both the 2018 event and a set of 19 identified analogues (including the former) for the period 1959–2022. Evidence is given that La Niña conditions in the tropical Pacific and upstream North Atlantic cyclones play an important role as a trigger for these events. Ensuing two-way tropospheric-stratospheric coupling and eddy feedbacks provide extended-range persistence for negative NAO conditions. These results may help improve the prediction of such exceptional events.