Climate change impacts negatively vulnerable regions such as West African countries like Senegal, through an increase of climate extremes. The objectives of this study is to analyze the future evolution of the extreme temperature events and their impacts on human health in Senegal during the cold (DJF), hot (MAM) and wet seasons (JAS) under the greenhouse gas scenarios RCP4.5 and RCP8.5 using Climate projections of five (5) regional climate models (RCMs) of the Coordinated Regional Climate Downscaling Experiment (CORDEX) program. The results show that the biases of the RCMs are globally low especially their ensemble mean of the RCMs. This ensemble mean was afterwards considered in the analysis of the climate extremes in the near (2021-2050) and far future (2071-2100). When considering the near future, the frequency of the hot nights (Tn90p) increases under the scenario RCP8.5 (up to 90%) during the rainy season in the south of the country. As for the percentage of the hot days (Tx90p), it may reach approximately 70% under the scenario RCP8.5 in DJF over the majority of the country. Moreover, a strong increase of Tn90p and Tx90p is also diagnosed during the far future with values exceeding 80% over most parts of the country. Concerning the evolution of the heat wave magnitude index-daily, the ensemble mean of all models shows that the heat waves are more severe in MAM and JAS under both scenarios during the near and the far future over most parts of the country. To estimate the potential impacts of this heat stress on the human health, the heat index and the humidex are used. The analysis of the heat index shows that the sanitary risks are more perceptible over the whole country during the rainy season with values reaching the symptom band II for both scenarios during the far future. As for the humidex, it is characterized by a gradual increase from the historical period to the far future. This analysis highlights the fact that appropriate adaptation measures should be considered to tackle efficiently the increase of temperature extremes which may impact negatively the human health.

The aim of this study is to simulate the impact of mineral dust emissions from the Sahel–Saharan zone on temperature extremes over the Sahel. To achieve this goal, we performed two numerical simulations: one with the standard version of the regional climate model RegCM4 (no dust run) and another one with the same version of this model incorporating a dust module (dust run). The difference between both versions of the model allowed to isolate the impacts of mineral dust emissions on temperature extremes. The results show that the accumulation of mineral dust into the atmosphere leads to a decrease of the frequency of warm days, very warm days, and warm nights over the Sahel. This decrease is higher during the MAM (March-April-May) and JJA (June-July-August) periods especially in the northern and western parts of the Sahel. The impact of the mineral dust emissions is also manifested by a decrease of the frequency of tropical nights especially during MAM in the northern Sahel. When considering the warm spells, mineral particles tend to weaken them especially in MAM and JJA in the northern Sahel. To estimate the potential impacts of the mineral dust accumulation on heat stress, the heat index and the humidex are used. The analysis of the heat index shows that the dust impact is to reduce the health risks particularly in the northern Sahel during the MAM period, in the western Sahel during JJA, and in the southern and the northeastern parts of the Sahel during the SON (September-October-November) period. As for the humidex, it is characterized by a decrease especially in the northern Sahel for all seasons. This reduction of the occurrence of thermal extremes may have a positive effect on the energy demand for cooling and on global health. However, the accumulation of dust particles in the atmosphere may also increase the meningitis incidence and prevalence.

This work aims at characterizing the conditional probability of single or consecutive dry and wet days in West Africa using the first-order Markov chain approach during the monsoon season (June to October). The results show that the probabilities of having a wet day (P W ), a wet day preceded by another wet day (P WW ) and a wet day preceded by a dry day (P DW ) are stronger in regions where the rainfall is maximum (mountain regions). In contrast, the probabilities of having a dry day (P D ), a dry day preceded by a wet day (P WD ) and a dry day preceded by another dry day (P DD ) are lower in the regions with higher precipitation. The seasonal cycle of P WW (P DD ) is consistent with that of P W (P D ), respectively in Western Sahel and Central Sahel regions. At the interannual timescale, MK test results show that P W and P DW (P D and P DD ) exhibit statistically significant increasing (decreasing) trends the Western Sahel and the Central Sahel. Besides, the shorter dry spells (3 days) show statistically significant decreasing trends only in the Western Sahel. The longer dry spells (5, 7 and 10 days) show statistically significant downward trends over the Western and Central Sahel. Wet spells probabilities show non-significant decreasing trends in all sub-domains, except in the Western Sahel for the 10 days spells. Knowledge of theses probabilities will contribute to develop efficient strategies for water resources management and agricultural decision making in West African countries.

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This work uses the Weibull distribution for assessing the wind potential in Senegal; a country located in West Africa. In this study, data from the ERA5 reanalysis and the Ziguinchor station were used to characterize the spatio-temporal variability of wind and its available power density at 10 m and 100 m of altitude. The results showed that the wind potential was stronger on the coast and the north-western part of the country. A case study was carried out in the Basse Casamance on five (5) different sites located on the coast and inland (Kafountine, Diembering, Kabrousse, Bignona, and Ziguinhor). The results show good wind potentials in the coastal areas: Kabrousse, Kafountine, and Diembering. The most favourable period for wind power production is the winter. The ERA5 data and those of the Ziguinchor weather station were also compared. The results showed that the annual average wind power density calculated with the ERA5 reanalysis was slightly higher than that of the data from the station. The wind rose's analysis, an essential parameter of the turbine's orientation, shows that the dominant wind direction in the Basse Casamance is northwest. In the last part of the study, an analysis of the choice of wind turbines adapted to the Ziguinchor site was carried out. Finally, this study provides the basic knowledge necessary for better planning of wind power projects in Senegal, especially in the Basse Casamance area.