Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales

• Published in: Nature Communications
• Main Authors: Sheen, KL, Smith, D, Dunstone, N, Eade, R, Rowell, D, Vellinga, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Nature 2017
• Subjects: North Atlantic
• Online Access: http://hdl.handle.net/10871/27698; https://doi.org/10.1038/ncomms14966

This is the final version of the article. Available from Springer Nature via the DOI in this record. Summer rainfall in the Sahel region of Africa exhibits one of the largest signals of climatic variability and with a population reliant on agricultural productivity, the Sahel is particularly vulnerable to major droughts such as occurred in the 1970s and 1980s. Rainfall levels have subsequently recovered, but future projections remain uncertain. Here we show that Sahel rainfall is skilfully predicted on inter-annual and multi-year (that is, >5 years) timescales and use these predictions to better understand the driving mechanisms. Moisture budget analysis indicates that on multi-year timescales, a warmer north Atlantic and Mediterranean enhance Sahel rainfall through increased meridional convergence of low-level, externally sourced moisture. In contrast, year-to-year rainfall levels are largely determined by the recycling rate of local moisture, regulated by planetary circulation patterns associated with the El Niño-Southern Oscillation. Our findings aid improved understanding and forecasting of Sahel drought, paramount for successful adaptation strategies in a changing climate. This work was supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101) and the EU FP7 SPECS project. The contribution of D.P.R. has received funding from the NERC/DFID Future Climate for Africa programme under the AMMA-2050 project, grant number NE/M019977/1.