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Multi-proxy summer and winter precipitation reconstruction for southern Africa over the last 200 years |
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| Authors: | Raphael Neukom David J Nash Georgina H Endfield Stefan W Grab Craig A Grove Clare Kelso Coleen H Vogel Jens Zinke |
| Institution: | 1. Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland 2. Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland 3. School of Environment and Technology, University of Brighton, Lewes Road, Brighton, BN2 4GJ, UK 4. School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand (Wits), Private Bag 3, Johannesburg, 2050, South Africa 5. School of Geography, University of Nottingham, University Park, Nottingham, NG7 2RD, UK 6. Department of Marine Geology, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands 7. Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa 8. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Hatfield, Private Bag X20, Pretoria, 0028, South Africa 10. Australian Institute of Marine Science, Nedlands, WA, 6009, Australia 9. School of Earth and Environment, University of Western Australia Oceans Institute, 35 Stirling Highway, Crawley, WA, 6009, Australia |
| Abstract: | This study presents the first consolidation of palaeoclimate proxy records from multiple archives to develop statistical rainfall reconstructions for southern Africa covering the last two centuries. State-of-the-art ensemble reconstructions reveal multi-decadal rainfall variability in the summer and winter rainfall zones. A decrease in precipitation amount over time is identified in the summer rainfall zone. No significant change in precipitation amount occurred in the winter rainfall zone, but rainfall variability has increased over time. Generally synchronous rainfall fluctuations between the two zones are identified on decadal scales, with common wet (dry) periods reconstructed around 1890 (1930). A strong relationship between seasonal rainfall and sea surface temperatures (SSTs) in the surrounding oceans is confirmed. Coherence among decadal-scale fluctuations of southern African rainfall, regional SST, SSTs in the Pacific Ocean and rainfall in south-eastern Australia suggest SST-rainfall teleconnections across the southern hemisphere. Temporal breakdowns of the SST-rainfall relationship in the southern African regions and the connection between the two rainfall zones are observed, for example during the 1950s. Our results confirm the complex interplay between large-scale teleconnections, regional SSTs and local effects in modulating multi-decadal southern African rainfall variability over long timescales. |
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