Uncertainties in the Annual Cycle of Rainfall Characteristics over West Africa in CMIP5 Models
1
Laboratoire de Physique de l’Atmosphère et de l’Océan - Siméon Fongang (LPAO-SF), Université Cheikh Anta Diop de Dakar, Dakar-Fann BP 5085, Senegal
2
Centre National de Recherches Météorologiques, CNRM/UMR 3589 CNRS et Météo-France, 31057 Toulouse, France
3
Institute of Meteorology and Climate Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), 82467 Garmisch-Partenkirchen, Germany
*
Author to whom correspondence should be addressed.
Atmosphere 2020, 11(2), 216; https://doi.org/10.3390/atmos11020216
Received: 15 December 2019 / Revised: 15 January 2020 / Accepted: 20 January 2020 / Published: 20 February 2020
(This article belongs to the Special Issue West African Monsoon Climate Dynamics and Impacts: Past, Present and Future)
We analyse uncertainties associated with the main features of the annual cycle of West African rainfall (amplitude, timing, duration) in 15 CMIP5 simulations over the Sahelian and Guinean regions with satellite daily precipitation estimates. The annual cycle of indices based on daily rainfall such as the frequency and the intensity of wet days, the consecutive dry (CDD) and wet (CWD) days, the 95th percentile of daily rainfall (R95), have been assessed. Over both regions, satellite datasets provide more consistent results on the annual cycle of monthly precipitation than on higher-frequency rainfall indices, especially over the Guinean region. By contrast, CMIP5 simulations display much higher uncertainties in both the mean precipitation climatology and higher-frequency indices. Over both regions, most of them overestimate the frequency of wet days. Over the Guinean region, the difficulty of models to represent the bimodality of the annual cycle of precipitation involves systematic biases in the frequency of wet days. Likewise, we found strong uncertainties in the simulation of the CWD and the CDD over both areas. Finally, models generally provide too early (late) onset dates over the Sahel (the Guinean region) and overestimate rainfall during the early and late monsoon phases. These errors are strongly coupled with errors in the latitudinal position of the ITCZ and do not compensate at the annual scale or when considering West Africa as a whole.
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Keywords:
West Africa; rainfall; annual cycle; CMIP5 models; onset; cessation; extremes; uncertainties
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MDPI and ACS Style
Sow, M.; Diakhaté, M.; Dixon, R.D.; Guichard, F.; Dieng, D.; Gaye, A.T. Uncertainties in the Annual Cycle of Rainfall Characteristics over West Africa in CMIP5 Models. Atmosphere 2020, 11, 216. https://doi.org/10.3390/atmos11020216
AMA Style
Sow M, Diakhaté M, Dixon RD, Guichard F, Dieng D, Gaye AT. Uncertainties in the Annual Cycle of Rainfall Characteristics over West Africa in CMIP5 Models. Atmosphere. 2020; 11(2):216. https://doi.org/10.3390/atmos11020216
Chicago/Turabian StyleSow, Magatte; Diakhaté, Moussa; Dixon, Ross D.; Guichard, Françoise; Dieng, Diarra; Gaye, Amadou T. 2020. "Uncertainties in the Annual Cycle of Rainfall Characteristics over West Africa in CMIP5 Models" Atmosphere 11, no. 2: 216. https://doi.org/10.3390/atmos11020216
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