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Climate change is universally occurring but probable fluctuations are not anticipated to be uniform worldwide; rather, there may be local differences. Thus, there is a need to investigate the trend and variations at the local and watershed levels to comprehend the magnitude of the change. This study was conducted to determine the trend of rainfall and temperature and assess their dependability. In this study, mean monthly and annual rainfall and temperature were analysed to determine the variability in magnitude over the period 1984-2014 at different stations. The non-parametric trend detector, Mann-Kendall test (MK) and trend magnitude detector, Sen’s Slope (SS) were used to reveal the trend and magnitude of rainfall and temperature, respectively. The largest increasing slope of significant annual precipitation occurred in November with a magnitude of 1.68 mm/y in Tordzinu. October recorded the most reliable rainfall at Kpetoe with a Coefficient of Variation (CV) of 0.3. The highest maximum monthly rainfall occurred in May, 2005 at Tordzinu with a magnitude of 522.2mm for the period under review. The minimum and maximum temperature increased by 0.2oC and 0.8oC respectively at Kpetoe and also 0.2oC and 0.5oC at Tordzinu per decade respectively.

International audience; As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, extensive in-situ measurements of the southern West African atmospheric boundary layer (ABL) have been performed at three supersites Kumasi (Ghana), Savè (Benin) and Ile-Ife (Nigeria) during the 2016 monsoon period (June and July). The measurements were designed to provide data for advancing our understanding of the relevant processes governing the formation, persistence and dissolution of nocturnal low-level stratus clouds and their influence on the daytime ABL in southern West Africa. An extensive low-level cloud deck often forms during the night and persists long into the following day strongly influencing the ABL diurnal cycle. Although the clouds are of a high significance for the regional climate, the dearth of observations in this region has hindered process understanding. Here, an overview of the measurements ranging from near-surface observations, cloud characteristics, aerosol and precipitation to the dynamics and thermodynamics in the ABL and above, and data processing is given. So-far achieved scientific findings, based on the dataset analyses, are briefly overviewed.

Nowcasting (weather forecasting predictions from zero to several hours) has enormous value and potential in Africa, where populations and economic activity are highly vulnerable to rapidly changing weather conditions. Timely issuing of warnings, a few hours before an event, can enable the public and decision-makers to take action. Rainfall radar estimates are not widely available in Africa, nor likely to be in the coming years, and numerical weather prediction (NWP) currently has low skill over the African continent. Therefore, for the delivery of nowcasting in Africa, satellite products are the best practical option and needed urgently (Roberts et al., 2021). Fifteen minute (or faster) updates of MSG (Meteosat Second Generation) images and NWC-SAF (Nowcasting Satellite Applications Facility) products are crucial for nowcasting to warn users (e.g. fisherfolk on Lake Victoria, flooding in urban areas, etc.) on pending severe storms. The possibility to have such products every 10 minutes, as well as data from the forthcoming MTG (Meteosat Third Generation) lightning imager, would be highly beneficial to all African countries, saving lives and livelihoods where high population growth and the most extreme impacts of climate change combine.

Stratospheric profiles of O3, NO2, and NO3 were retrieved from lunar transmitted spectra measured by SCIAMACHY over high southern latitude (60Ã °S - 90Ã °S), from March to June 2003 and January to June 2004. The global spectral fitting method by the differential optical depth approach was applied to simultaneously fit O3 and NO2 using the spectral range of 430-460 nm and 510-560 nm. Furthermore, NO3 was fitted using the visible spectral range of 615-680 nm containing NO3 intense absorption bands at 623 nm and 662 nm. Validation of the retrieved SCIAMACHY O3 and NO2 profiles were carried out. O3 profiles were compared with HALOE,POAM-III, SAGE-II and -III, and MIPAS. Whereas NO2 profiles were compared with HALOE, MIPAS, and SAGE-III. The validation results show that the quality of SCIAMACHY O3profiles is high, within 10-25% and 10-35% for O3 and NO2 respectively. To test our current understanding of NO3 chemistry, the retrieved NO3 vertical profiles were compared with a full photochemical model and a relatively simple steady state model. The calculations from a full photochemical model constrained by retrieved O3 and analyzed ECMWF temperatures in the altitude range between 24 to 45 km. Below about 35-40 km, observed NO3 is well reproduced by photochemical steady state calculations. Differences between observed and modeled NO3 are within the estimated accuracy of 20-35%, demonstrating that we have a reasonable understanding of the behavior of NO3 in the polar stratosphere.