Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator
Abstract During strong El Niño events, below-average rainfall is expected in large parts of southern Africa. The 1992 El Niño season was associated with one of the worst drought episodes in large parts of South Africa. Using reanalysis data set from NCEP-NCAR, this study examined circulation types (...
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crspringernat:10.1007/s00704-021-03741-7 2023-05-15T18:21:18+02:00 Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator Ibebuchi, Chibuike Chiedozie Julius-Maximilians-Universität Würzburg 2021 http://dx.doi.org/10.1007/s00704-021-03741-7 https://link.springer.com/content/pdf/10.1007/s00704-021-03741-7.pdf https://link.springer.com/article/10.1007/s00704-021-03741-7/fulltext.html en eng Springer Science and Business Media LLC https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 CC-BY Theoretical and Applied Climatology volume 146, issue 1-2, page 723-740 ISSN 0177-798X 1434-4483 Atmospheric Science journal-article 2021 crspringernat https://doi.org/10.1007/s00704-021-03741-7 2022-01-04T16:52:08Z Abstract During strong El Niño events, below-average rainfall is expected in large parts of southern Africa. The 1992 El Niño season was associated with one of the worst drought episodes in large parts of South Africa. Using reanalysis data set from NCEP-NCAR, this study examined circulation types (CTs) in Africa south of the equator that are statistically related to the El Niño signal in the southwest Indian Ocean and the implication of this relationship during the 1992 drought episode in South Africa. A statistically significant correlation was found between the above-average Nino 3.4 index and a CT that features widespread cyclonic activity in the tropical southwest Indian Ocean, coupled with a weaker state of the south Indian Ocean high-pressure. During the analysis period, it was found that the El Niño signal enhanced the amplitude of the aforementioned CT. The impacts of the El Niño signal on CTs in southern Africa, which could have contributed to the 1992 severe drought episode in South Africa, were reflected in (i) robust decrease in the frequency of occurrence of the austral summer climatology pattern of atmospheric circulation that favors southeasterly moisture fluxes, advected by the South Indian Ocean high-pressure; (ii) modulation of easterly moisture fluxes, advected by the South Atlantic Ocean high-pressure, ridging south of South Africa; (iii) and enhancement of the amplitude of CTs that both enhances subsidence over South Africa, and associated with the dominance of westerlies across the Agulhas current. Under the ssp585 scenario, the analyzed climate models suggested that the impact of radiative heating on the CT significantly related to El Niño might result in an anomalous increase in surface pressure at the eastern parts of South Africa. Article in Journal/Newspaper South Atlantic Ocean Springer Nature (via Crossref) Austral Indian Theoretical and Applied Climatology |
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Springer Nature (via Crossref) |
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language |
English |
topic |
Atmospheric Science |
spellingShingle |
Atmospheric Science Ibebuchi, Chibuike Chiedozie Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
topic_facet |
Atmospheric Science |
description |
Abstract During strong El Niño events, below-average rainfall is expected in large parts of southern Africa. The 1992 El Niño season was associated with one of the worst drought episodes in large parts of South Africa. Using reanalysis data set from NCEP-NCAR, this study examined circulation types (CTs) in Africa south of the equator that are statistically related to the El Niño signal in the southwest Indian Ocean and the implication of this relationship during the 1992 drought episode in South Africa. A statistically significant correlation was found between the above-average Nino 3.4 index and a CT that features widespread cyclonic activity in the tropical southwest Indian Ocean, coupled with a weaker state of the south Indian Ocean high-pressure. During the analysis period, it was found that the El Niño signal enhanced the amplitude of the aforementioned CT. The impacts of the El Niño signal on CTs in southern Africa, which could have contributed to the 1992 severe drought episode in South Africa, were reflected in (i) robust decrease in the frequency of occurrence of the austral summer climatology pattern of atmospheric circulation that favors southeasterly moisture fluxes, advected by the South Indian Ocean high-pressure; (ii) modulation of easterly moisture fluxes, advected by the South Atlantic Ocean high-pressure, ridging south of South Africa; (iii) and enhancement of the amplitude of CTs that both enhances subsidence over South Africa, and associated with the dominance of westerlies across the Agulhas current. Under the ssp585 scenario, the analyzed climate models suggested that the impact of radiative heating on the CT significantly related to El Niño might result in an anomalous increase in surface pressure at the eastern parts of South Africa. |
author2 |
Julius-Maximilians-Universität Würzburg |
format |
Article in Journal/Newspaper |
author |
Ibebuchi, Chibuike Chiedozie |
author_facet |
Ibebuchi, Chibuike Chiedozie |
author_sort |
Ibebuchi, Chibuike Chiedozie |
title |
Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
title_short |
Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
title_full |
Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
title_fullStr |
Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
title_full_unstemmed |
Revisiting the 1992 severe drought episode in South Africa: the role of El Niño in the anomalies of atmospheric circulation types in Africa south of the equator |
title_sort |
revisiting the 1992 severe drought episode in south africa: the role of el niño in the anomalies of atmospheric circulation types in africa south of the equator |
publisher |
Springer Science and Business Media LLC |
publishDate |
2021 |
url |
http://dx.doi.org/10.1007/s00704-021-03741-7 https://link.springer.com/content/pdf/10.1007/s00704-021-03741-7.pdf https://link.springer.com/article/10.1007/s00704-021-03741-7/fulltext.html |
geographic |
Austral Indian |
geographic_facet |
Austral Indian |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
Theoretical and Applied Climatology volume 146, issue 1-2, page 723-740 ISSN 0177-798X 1434-4483 |
op_rights |
https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s00704-021-03741-7 |
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Theoretical and Applied Climatology |
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1766200489662218240 |