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CR 91:145-158 (2023)  -  DOI:

Atmospheric response to SST isolation on the interannual variability scale during ENSO episodes

Rildo Gonçalves de Moura1,*, Francis Wagner Silva Correia2, José Augusto Paixão Veiga2, Vinicius Buscioli Capistrano3, Paulo Yoshio Kubota4

1Postdoctorate Program in Environmental Engineering (PPGEA/UFPR), Federal University of Paraná, Av. Cel. Francisco H. dos Santos 100, Jardim das Américas, 81530-000 Curitiba, Paraná, Brazil
2University of the State of Amazonas, Av. Darcy Vargas 1200, Parque 10 de Novembro, 69065-020 Manaus, Amazonas, Brazil
3Federal University of Mato Grosso do Sul, Av. Costa e Silva, Cidade Universitária, 79070-900 Campo Grande, Mato Grosso do Sul, Brazil
4Institute for Space Research, Center for Weather Forecast and Climate Studies, Rodovia Presidente Dutra, Km 40, 12630-000 Cachoeira Paulista, São Paulo, Brazil
*Corresponding author:

ABSTRACT: This study aimed to evaluate the impact of SST, isolated on an interannual scale, on the dynamics of atmospheric circulation, especially in the tropical region of the Pacific and Atlantic Oceans. Although there are several studies based on observations and numerical modeling, the isolated effects caused by a specific mode of variability are not yet fully known. For this purpose, the Brazilian Global Atmospheric Model (BAM) forced with an isolated interannual SST, obtained by Moura et al. (2022), was used as a surface boundary condition. To quantify the response of the atmosphere to this time scale, anomalous atmospheric fields were obtained from a reference numerical experiment, where unfiltered SST fields were used as boundary conditions. The effects of the interannual time scale on the dynamics of atmospheric circulation were evaluated for the positive and negative phases of ENSO. In general, when the atmosphere is forced by the isolated interannual variability mode, the atmospheric circulation patterns become weaker than the variability obtained by the non-isolated mode. This weakening is statistically significant and independent of the positive or negative phase of ENSO. The isolated interannual mode significantly reduced the areas of precipitation and its intensity in South America, especially over the Amazon basin and northeastern Brazil. However, changes in precipitation in these regions are more evident in the positive phase of ENSO than in the negative phase. The SST filtering methodology and the use of an atmospheric general circulation model applied in this study adequately revealed the purely dynamic effects of the isolated interannual mode on the atmosphere.

KEY WORDS: Climate variability · General atmospheric circulation · ENSO · Brazilian Global Atmospheric Model · BAM

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Cite this article as: Moura RG, Correia FWS, Veiga JAP, Capistrano VB, Kubota PY (2023) Atmospheric response to SST isolation on the interannual variability scale during ENSO episodes. Clim Res 91:145-158.

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