Ensemble-based CMIP5 simulations of West African summer monsoon rainfall: current climate and future changes
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The West African summer monsoon (WASM) rainfall is of significant socioeconomic importance. Therefore, its response to climate change is of great concern to climate scientists. Based on observations, reanalysis, and multi-model ensemble mean (EnsMean) simulations of Coupled Model Intercomparison Project phase 5 (CMIP5) models, the responses of WASM rainfall, as well as some relevant atmospheric features, to global warming are investigated. Results from the historical period (1980–2005) indicate that EnsMean reasonably reproduced the characteristics of WASM rainfall, and the strength and position of the upper-level Tropical Easterly Jet (TEJ) and mid-level African Easterly Jet (AEJ). Under global warming, EnsMean exhibits localized future changes in spatial rainfall pattern; specifically, a statistically significant increase (decrease) is evident over the central-eastern (western) Sahel subregion. Similarly, the annual cycle exhibits a decrease (increase) in pre-monsoon (post-monsoon) rainfall over the region, evident over the Sahel subregion. Increased surface evaporation and enhanced atmospheric moisture convergence are notable over the region of increasing WASM rainfall, while a weakened and possible alteration of large-scale atmospheric circulation features is evident over the study area.
The authors appreciate the World Climate Research Program’s Working Group on Coupled Modeling, which is responsible for CMIP5, and we also thank the climate modeling groups listed in Table 1 for producing and making available their model output. We are also grateful to the services that have operated the GPCP, CRU, and NCEP/NCAR datasets.
This work is supported by the National Nature Science Foundation of China Grant (41675062) and the Research Grants Council of the Hong Kong Special Administrative Region, China (CityU 11305715 and 11335316). The first author is a recipient of a research studentship provided by the City University of Hong Kong (CityU).
- Adler, et al (2016) An update (Version 2.3) of the GPCP monthly analysis. (in preparation)Google Scholar
- Akinsanola AA, Zhou W (2018) Projections of West African summer monsoon rainfall extremes from two CORDEX models. Clim Dyn. https://doi.org/10.1007/s00382-018-4238-8
- Christensen JH, et al (2007) Regional climate projections. In: Solomon, S., et al. (Eds.), Climate change 2007: the physical science basis. Cambridge University Press, pp. 847–940.Google Scholar
- Cook KH (1999) Generation of the African easterly jet and its role in determining West African precipitation. J Clim 12:1165–1184. https://doi.org/10.1175/15200442(1999)012,1165:GOTAEJ.2.0.CO;2. CrossRefGoogle Scholar
- Hartmann DL, Klein Tank AMG, Rusticucci M, Alexander LV, Brönnimann S, Charabi Y, Dentener FJ, Dlugokencky EJ, Easterling DR, Kaplan A, Soden BJ, Thorne PW, Wild M, Zhai PM (2013) Observations: atmosphere and surface. In: Stocker TF, Qin D, Plattner G-K, Tignor MMB, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change (2013) the physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge, United Kingdom. Cambridge University Press, New YorkGoogle Scholar
- Hourdin F, Musat I, Guichard F, Ruti PM, Favot F, Filiberti MA, Pham M, Grandpeix JY, Polcher J, Marquet P, Boone A, Lafore JP, Redelsperger JL, Dellaquila A, Losada DT, Khadre TA, Gallee H (2010) AMMA—model intercomparison project. Bull Am Meteorol Soc 91:95–104. https://doi.org/10.1175/2009BAMS2791.1. CrossRefGoogle Scholar
- IPCC (2013) Climate change 2013: The physical science basis, in Working Group I Contribution to the Fifth Assessment Report of the IPCC, edited by T. F. Stocker, Cambridge Univ. Press, Cambridge.Google Scholar
- Li RQ, Lv SH, Han B (2013) Simulations of Asian-Australian monsoon circulation and variability by 10 CMIP5 models. J Trop Meteorol 29(5):749–758Google Scholar
- Li R, Lü S, Han B et al (2015) Connections between the South Asian summer monsoon and the tropical sea surface temperature in CMIP5. J Meteorol Res 29:106. https://doi.org/10.1007/s13351-014-4031-5
- Nikulin G, Jones C, Giorgi F, Asrar G, Buchner M, Cerezo-Mota R, Christensen OB, Deque M, Fernandez J, Hansler A, van Meijgaard E, Samuelsson P, Sylla MB, Sushama L (2012) Precipitation climatology in an ensemble of CORDEX-Africa regional climate simulations. J Clim 25:6057–6078. https://doi.org/10.1175/JCLI-D-11-00375.1 CrossRefGoogle Scholar
- Odoulami RC, Akinsanola AA (2017) Recent assessment of West African summer monsoon daily rainfall trends. Weather. https://doi.org/10.1002/wea.2965
- Sylla MB, Gaye AT, Jenkins GS (2012) On the fine-scale topography regulating changes in atmospheric hydrological cycle and extreme rainfall over West Africa in regional climate model projections. Int J Geophys 2012:981649. https://doi.org/10.1155/2012/981649
- Sylla MB, Diallo I, Pal JS (2013) West African monsoon in state-of-the-science regional climate models. Climate variability: regional and thematic patterns, A. Tarhule, Ed., InTech, 3–36, https://doi.org/10.5772/55140.
- Thorncroft CD, Blackburn M (1999) Maintenance of the African Easterly Jet. Q J Roy Meteorol Soc 125:763–786Google Scholar
- van Vuuren DP, Edmonds J, Kainuma M, Riahi K, Thomson A, Hibbard K, Hurtt GC, Kram T, Krey V, Lamarque JF, Masui T, Meinshausen M, Nakicenovic N, Smith SJ, Rose SK (2011) The representative concentration pathways: an overview. Clim Chang 109(1–2):5–31. https://doi.org/10.1007/s10584-011-0148-z. CrossRefGoogle Scholar
- Xin XG et al (2013) How well does BCC_CSM1.1 reproduce the 20th century climate change over China? Atmos Oceanic Sci Lett 6:21–26Google Scholar