The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer
This paper examines the relative role of the Indian Ocean basin-wide (IOBW) mode and El Niño–Southern Oscillation (ENSO) in the atmospheric circulation and rainfall interannual variations over South America (SA) during southern summer of the 1951‒2016 period. The effects of the warm IOBW and El Niño...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-08-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/12/9/1094 |
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| author | Mary T. Kayano Rita V. Andreoli Wilmar L. Cerón Rodrigo A. F. Souza |
| author_facet | Mary T. Kayano Rita V. Andreoli Wilmar L. Cerón Rodrigo A. F. Souza |
| author_sort | Mary T. Kayano |
| collection | DOAJ |
| description | This paper examines the relative role of the Indian Ocean basin-wide (IOBW) mode and El Niño–Southern Oscillation (ENSO) in the atmospheric circulation and rainfall interannual variations over South America (SA) during southern summer of the 1951‒2016 period. The effects of the warm IOBW and El Niño (EN) events, and of the cold IOBW and La Niña (LN) events are examined using partial correlations. The ENSO and IOBW modes, through the associated large-scale and regional anomalous circulation patterns, induce contrasting effects on the rainfall in northeastern SA. The EN without the warm IOBW effect induces anomalously dry conditions over eastern Amazon and part of northeastern Brazil (NEB) through anomalous sinking motions of the EN-related anomalous Walker and Hadley cells and strong moisture divergence associated with a vigorous anticyclone over tropical South Atlantic (TSA) and SA. The warm IOBW without the EN effect induces anomalously wet conditions in NEB, which is marginally related to the anomalous Walker and Hadley cells but is modulated by an anticyclone over SA between the equator and 20° S, and a cyclone in the southwestern Atlantic between 20° S and 40° S. The results here might be relevant for climate monitoring and modeling studies. |
| first_indexed | 2024-03-10T07:54:10Z |
| format | Article |
| id | doaj.art-6744d8e750044b4faa7c0526e5b27c8c |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-10T07:54:10Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-6744d8e750044b4faa7c0526e5b27c8c2023-11-22T11:59:10ZengMDPI AGAtmosphere2073-44332021-08-01129109410.3390/atmos12091094The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral SummerMary T. Kayano0Rita V. Andreoli1Wilmar L. Cerón2Rodrigo A. F. Souza3Coordenação Geral de Ciências da Terra, Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758, São José dos Campos 12227-010, SP, BrazilEscola Superior de Tecnologia, Universidade do Estado do Amazonas, Av. Darcy Vargas, 1200, Parque 10 de Novembro, Manaus 69065-020, AM, BrazilDepartment of Geography, Faculty of Humanities, Universidad del Valle, Calle 13 # 100-00, Cali P.O. Box 25360, ColombiaEscola Superior de Tecnologia, Universidade do Estado do Amazonas, Av. Darcy Vargas, 1200, Parque 10 de Novembro, Manaus 69065-020, AM, BrazilThis paper examines the relative role of the Indian Ocean basin-wide (IOBW) mode and El Niño–Southern Oscillation (ENSO) in the atmospheric circulation and rainfall interannual variations over South America (SA) during southern summer of the 1951‒2016 period. The effects of the warm IOBW and El Niño (EN) events, and of the cold IOBW and La Niña (LN) events are examined using partial correlations. The ENSO and IOBW modes, through the associated large-scale and regional anomalous circulation patterns, induce contrasting effects on the rainfall in northeastern SA. The EN without the warm IOBW effect induces anomalously dry conditions over eastern Amazon and part of northeastern Brazil (NEB) through anomalous sinking motions of the EN-related anomalous Walker and Hadley cells and strong moisture divergence associated with a vigorous anticyclone over tropical South Atlantic (TSA) and SA. The warm IOBW without the EN effect induces anomalously wet conditions in NEB, which is marginally related to the anomalous Walker and Hadley cells but is modulated by an anticyclone over SA between the equator and 20° S, and a cyclone in the southwestern Atlantic between 20° S and 40° S. The results here might be relevant for climate monitoring and modeling studies.https://www.mdpi.com/2073-4433/12/9/1094climate variabilitySouth Americarainfallteleconnectionstropical Indian oceanRossby wave train |
| spellingShingle | Mary T. Kayano Rita V. Andreoli Wilmar L. Cerón Rodrigo A. F. Souza The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer Atmosphere climate variability South America rainfall teleconnections tropical Indian ocean Rossby wave train |
| title | The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer |
| title_full | The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer |
| title_fullStr | The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer |
| title_full_unstemmed | The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer |
| title_short | The Role of the Indian Ocean Basin-Wide and El Niño–Southern Oscillation Modes in Interannual Rainfall Variability over South America during Austral Summer |
| title_sort | role of the indian ocean basin wide and el nino southern oscillation modes in interannual rainfall variability over south america during austral summer |
| topic | climate variability South America rainfall teleconnections tropical Indian ocean Rossby wave train |
| url | https://www.mdpi.com/2073-4433/12/9/1094 |
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