The high‐frequency variability of Antarctic sea ice and polar cold air incursions over Amazonia

Abstract The cold air incursion over South America is associated with the frontal systems generated in the Antarctic region, and sea ice cover plays an important role in its formation. Little is known about how the high‐frequency variability of the coupled ocean–cryosphere‐atmosphere system affects...

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Bibliographic Details
Published in:International Journal of Climatology
Main Authors: Carpenedo, Camila Bertoletti, Campos, José Leandro Pereira Silveira, Ambrizzi, Tércio, Braga, Ricardo Burgo
Other Authors: Conselho Nacional de Desenvolvimento Científico e Tecnológico, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Fundação de Amparo à Pesquisa do Estado de São Paulo
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2021
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Online Access:http://dx.doi.org/10.1002/joc.7422
https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7422
https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.7422
https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7422
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Summary:Abstract The cold air incursion over South America is associated with the frontal systems generated in the Antarctic region, and sea ice cover plays an important role in its formation. Little is known about how the high‐frequency variability of the coupled ocean–cryosphere‐atmosphere system affects weather conditions in South America, especially in the Amazon region ‐ in tandem with the largest tropical forest on the planet and a key region of the global climate system. The results presented here suggest that the high‐frequency variability of the expansion of Antarctic sea ice extent (SIE) extremes, in the Ross Sea and Indian Ocean, modulate the cold air incursion over the Amazon in the southern winter 4 and 2 days after the expansion of SIE extremes, respectively. The SIE extremes can couple with the atmosphere, inducing Rossby waves that propagate and undergo amplification downstream from the Ross Sea and Indian Ocean during such extremes. In this way, the atmospheric wave train acquires a more southern spread over South America, reaching tropical latitudes after the SIE extremes. In non‐SIE extreme periods, the atmospheric wave train has a more zonal spread and reaches only the extratropical latitudes of the continent.