The Impact of ENSO on the South Atlantic Subtropical Dipole Mode

Autor(es)

Rodrigues, Regina R. ^[1] ; Campos, Edmo J. D. ^[2] ; Haarsma, Reindert ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fed Santa Catarina, Dept Geociencias, BR-88040970 Florianopolis, SC - Brazil

^[2] Univ Sao Paulo, Oceanog Inst, Sao Paulo - Brazil

^[3] Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt - Netherlands

• Tipo de documento: Artigo Científico
• Fonte: Journal of Climate; v. 28, n. 7, p. 2691-2705, APR 2015.
• Citações Web of Science: 16

Resumo

The impact of El Nino-Southern Oscillation (ENSO) on the South Atlantic subtropical dipole mode (SASD) is investigated using both observations and model simulations. The SASD is the dominant mode of coupled ocean-atmosphere variability in the South Atlantic. This study focuses on austral summer, when both ENSO and SASD peak. It is shown that negative SASD events are associated with central Pacific El Nino events by triggering the Pacific-South American wave train (PSA). The latter resembles the third leading mode of atmospheric variability in the Southern Hemisphere (PSA2) and causes a weakening and meridional shift of the South Atlantic subtropical high, which then generates the negative SASD events. On the other hand, a strengthening of the South Atlantic subtropical high related to central La Nina teleconnections causes positive SASD events. The results herein show that the PSA2, triggered by central Pacific ENSO events, connects the tropical Pacific to the Atlantic. This connection is absent from eastern Pacific ENSO events, which appear to initiate the second leading mode of atmospheric variability in the Southern Hemisphere (PSA1). It is for this reason that previous studies have found weak correlations between ENSO and SASD. These findings can improve the climate prediction of southeastern South America and southern Africa since these regions are affected by sea surface temperature anomalies of both the Pacific and Atlantic Oceans. (AU)

• Processo FAPESP: 10/01943-8 - Impactos de alterações no vazamento das agulhas sobre o Atlântico Sul (CALSA)
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 11/50552-4 - Impacto do Atlântico Sul na célula de circulação meridional e no clima
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático