Abstract
AbstractDuring 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.
Funder
Julius-Maximilians-Universität Würzburg
Publisher
Springer Science and Business Media LLC
Reference50 articles.
1. Baudoin M, Vogel C, Nortje Naik M (2017) Living with drought in South Africa: lessons learnt from the recent El Niño drought period. Int J Disaster Risk Reduct 23:128–137. https://doi.org/10.1016/j.ijdrr.2017.05.005
2. Bruwer JJ (1993) Drought policy in the Republic of South Africa. In: Wilhite DA (ed) Drought assessment, management, and planning: theory and case studies. Natural Resource Management and Policy, vol 2.Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-3224-8_11
3. Compagnucci RH, Richman MB (2008) Can principal component analysis provide atmospheric circulation or teleconnection patterns? Int J Climatol 28(6):703–726. https://doi.org/10.1002/joc.1574
4. Cook KH (2000) The South Indian Convergence Zone and Interannual Rainfall Variability over Southern Africa. J Clim 13(21):3789–3804. https://doi.org/10.1175/1520-0442(2000)013<3789:TSICZA>2.0.CO;2
5. Driver P (2014) Rainfall variability over Southern Africa. PhD Thesis, University of Cape Town, South Africa. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.913.1020&rep=rep1&type=pdf. Accessed 21 Mar 2021
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