Air quality degradation is a major issue in the large conurbations on the shore of the Gulf of Guinea. We present for the first time PM_2.5 time series collected in Cotonou, Benin, and Abidjan, Côte d'Ivoire, from February 2015 to March 2017. Measurements were performed in the vicinity of major combustion aerosol sources: Cotonou/traffic (CT), Abidjan/traffic (AT), Abidjan/landfill (AL) and Abidjan/domestic fires (ADF). We report the weekly PM_2.5 mass and carbonaceous content as elemental (EC) and organic (OC) carbon concentrations. We also measure the aerosol optical depth (AOD) and the Ångström exponent in both cities. The average PM_2.5 mass concentrations were 32 ± 32, 32 ± 24 and 28 ± 19 µg m⁻³ at traffic sites CT and AT and landfill site AL, respectively. The domestic fire site shows a concentration of 145 ± 69 µg m⁻³ due to the contribution of smoking and roasting activities. The highest OC and EC concentrations were also measured at ADF at 71 ± 29 and 15 ± 9 µg m⁻³, respectively, while the other sites present OC concentration between 8 and 12 µg m⁻³ and EC concentrations between 2 and 7 µg m⁻³. The OC ∕ EC ratio is 4.3 at CT and 2.0 at AT. This difference highlights the influence of two-wheel vehicles using gasoline in Cotonou compared to that of four-wheel vehicles using diesel fuel in Abidjan. AOD was rather similar in both cities, with a mean value of 0.58 in Cotonou and of 0.68 in Abidjan. The seasonal cycle is dominated by the large increase in surface mass concentration and AOD during the long dry season (December–February) as expected due to mineral dust advection and biomass burning activities. The lowest concentrations are observed during the short dry season (August–September) due to an increase in surface wind speed leading to a better ventilation. On the other hand, the high PM_2.5 ∕ AOD ratio in the short wet season (October–November) indicates the stagnation of local pollution.

Despite its rich hydrological and rainfall potential, Yomou prefecture is one of the most energy- lagging cities in the forest region. This is why people choose to use solar panels as an energy source. Although the use of these panels is considered as a solution to the energy problems in Yomou, it is clear that climatic factors (such as: solar radiation, temperature, humidity and precipitation) have a negative impact on the performance of the installed panels. The data used in this study were collected from the Meteonorm 8.2 site database for a period from January to December 2024 in Yomou prefecture. The data were processed and analyzed using PVsyst 8.0.5 software. The aim of this work is to study the impact of climatic factors on the performance of photovoltaic energy production in order to identify the causes of solar energy production losses in this locality. Statistical analysis tools are used to assess annual and seasonal trends in climate variables. Use graphs to illustrate the variation and correlation between these factors and photovoltaic performance. The results show that the solar potential is high, especially during the dry season (January to April and November), providing optimal conditions for solar production. However, the rainy season (June to September) reduces the efficiency of photovoltaic panels due to increased diffuse radiation. To maximize energy production, technologies such as bifacial panels or solar tracking systems are recommended. It is also important to manage the tilt of the panels and take into account changes in light index (Kt) and seasonal temperature. The integration of storage solutions and the adaptation of the system to local conditions will ensure continuous energy production throughout the year. The relative humidity in the locality is on average 70%, peaking during the wet season (May to October) and decreasing during the dry season (November to April). These seasonal changes can affect the performance of photovoltaic panels, highlighting the importance of having systems adapted to local climatic conditions.

This study focuses on the comparison of carbonaceous aerosol measurements in the air at Cotonou in 2015 compared to 2005. Working within the framework of two international programs, African Monsoon Multidisciplinary Analysis (AMMA) and Dynamics Aerosol-Cloud-Chemistry Interactions in West Africa (DACCIWA), monitoring data for PM2.5 microns were collected at one of the most polluted urban site of Cotonou (Dantokpa) in Benin (West Africa) in 2005 and 2015, respectively. The obtained results indicate that the carbonaceous aerosol measures, black carbon (BC), and organic carbon (OC) were higher in 2005 than those obtained in 2015. PM2.5 concentrations related mainly to traffic sources for two wheeled vehicles were 34 g/m³ in May 2005 and 28 µg/m³ in May 2015. In May 2005, OC and BC concentrations were from 15 µg/m³ and 2.3 µg/m³, while in May 2015, they were from 8 µg/m³ for OC and 1.3 µg/m³ for BC. In May 2005 and 2015, the total carbon (TC) accounted for 50% and 32% of the PM2.5, respectively. In this study, the OC/EC ratio exceeded 2.0, which confirms the presence of secondary organic aerosols.

Republic of Guinea is one of the West African countries which share form a border with the southern. The rainfall onset in this country is one of the major problems that the farmers face. For it, we determined with more precision, the rainy season onset in eight synoptic stations in Republic of Guinea: Boke, Conakry, Faranah, Kankan, Koundara, Labe, Mamou and NZerekore. Then, we studied the InterTropical Front (ITF) position compared to each station at the onset date. This work better analyses the atmospheric dynamics leading to rainfall particularity. We used the daily rainfall data provided by the National Meteorological Service of Guinea for (1991-2020) years and the dekadal (10-day) ITF position data produced by the National Oceanic and Atmospheric Administration (NOAA) for (1990-2021) years. Using these daily rain of the eight stations and the ITF data, we calculated, the dekadal, monthly and annual rain amount, then we established a relation between the ITF position and the precipitation for each station. Results obtained show that the rainy season begins on May 18th, April 20th, May 4th, May 14th, June 8th, May 12th, April 28th and March 20th in Boké, Conakry, Faranah, Kankan, Koundara, Labe, Mamou and NZerekore regions, respectively. Compared to these dates, the ITF is located 2247.77 km north of Boke, 2136.13 km north of Conakry, 2121.24 km north of Faranah, 2136.13 km north of Kankan, 2236.61 km north of Koundara, 2247.77 km north of Labe, 2236.61 km north of Mamou and 2136.13 km north of NZerekore. The good correlation is obtained between the ITF position and the monthly precipitations for eight regions. This study will allow farmers to know with more precision the rainfall onset in Republic of Guinea.

Air quality degradation is a major issue in the large conurbations on the shore of the gulf of Guinea. We present for the first time PM_2.5 time series collected in Cotonou, Benin and Abidjan, Cote d'Ivoire from February 2015 to March 2017. Measurements were performed in the vicinity of major combustion aerosol sources: Cotonou/Traffic (CT), Abidjan/Traffic (AT), Abidjan/Waste Burning (AWB) and Abidjan/Domestic Fires (ADF). We report the weekly PM_2.5 mass and carbonaceous content as Elemental (EC) and organic (OC) carbon concentrations. We also proceed to the measurements of the Aerosol Optical Depth (AOD) and the Angström exponent in both cities. The average PM_2.5 mass concentrations were 32 ± 32 μg/m³, 32 ± 24 μg/m³, 28 ± 19 μg/m³ at traffic sites CT and AT and waste burning site AWD, respectively. The domestic fire site shows concentration of 145 ± 69 μg/m³ due the contribution of smoking and grilling activities. The highest OC and EC concentrations were also measured at ADF at 71 ± 29 μg/m³ and 15 ± 9 μg/m³, respectively. While the other sites present OC concentration between 8 and 12 μg/m³ and EC concentrations between 2 and 7 μg/m³. The OC / EC ratio is 4.3 at CT and 2.0 at AT. This difference highlighs the influence of 2-wheels vehicles using 2-stoke mix in Cotonou compared to Abidjan. AOD were rather similar in both cities with a mean value of 0.58 in Cotonou and 0.68 in Abidjan. The seasonal cycle is dominated by the large increase in surface mass concentration and AOD during the main dry season (Dec.–Feb.) as expected due to mineral dust advection and biomass burning activities. The lowest concentrations are observed during the minor dry season (Aug.–Sept.) due to an increase in surface wind speed leading to a better ventilation. On the other hand, the high PM_2.5 / AOD ratio in the minor wet season (Oct.–Nov.) indicates the stagnation of local pollution.