a b s t r a c tNigerian agriculture is mainly rain-fed and basically dependent on the vagaries of weather especially rainfall. Nigeria today has about forty-four (44) weather observation stations which provide measurement of rainfall amount for different locations across the country. Hence, this study investigates change detection in rainfall pattern over each climatic zone of Nigeria. Data were collected for 90 years period for all the weather observation stations in Nigeria, while a subdivision was made to three (3) non-overlapping climate period of 30 years i.e. 1910-1939, 1940-1969 and 1970-1999. Statistical methods were utilized to justify any change in the average monthly and annual rainfall trend using probability density function and non-parametric tests such as the Pettitt test, Wilcoxon signed-rank test and paired sample test. Results show common change points and transitions from dry to wet (upward shift) in all climatic zones. Statistical tests performed on the data show that rainfall variation over each climatic zone is significant (po 0.05) between pairs of climate periods. Suggestions were therefore made at the end of the study on the use of the contained information for socio-economic improvement and agricultural development of the zones.

Satellite derived solar irradiance over 25 locations in the 5 climatic zones of Nigeria (tropical rainforest TRF, Guinea savannah GS, Sahel savannah SHS, Sudan savannah SUS, and Mangrove swamp forest MSF) was analyzed. To justify its use, the satellite data was tested for goodness of agreement with ground measured solar radiation data using 26-year mean monthly and daily data over 16 locations in the 5 climatic zones. The well-known R 2 , RMSE, MBE, and MPE statistical tests were used and good agreement was found. The 25 locations were grouped into the 5 climatic zones. Frequency distribution of global solar irradiance was done for each of the climatic zones. This showed that 46.88%, and 40.6% of the number of days (9794) over TRF and MSF, respectively, had irradiation within the range of 15.01-20.01 MJ/m 2 /day. For the GS, SHS, and SUS, 46.19%, 55.84% and 58.53% of the days had total irradiation within the range of 20.01-25.01 MJ/m 2 /day, respectively. Generally, in all the climatic zones, coefficients of variation of solar radiation were high and mean values were low in July and August. Contour maps showed that high and low values of global solar irradiance and clearness index were observed in the Northern and Southern locations of Nigeria, respectively.

Mineral dust over West Africa region modulates summer monsoon through direct radiative forcing. This study examined the impact of mineral dust radiative forcing on West Africa Monsoon variability with the aid of Regional Climate Model (RegCM4) at 50 km grid resolution driven by ERA Interim re-analysis. Three experiments were performed; first with the non-dust aerosol version of the model (CONTROL), and second with the dust aerosol module (DUST) and with an increase in the dust concentration (DOUBLE DUST). The simulation was run from October, 2004 to December, 2005 over West Africa domain with the first 3 months taken as spin up for model stability. The result shows that there was no significant change with Control and Dust case experiment but as the dust AOD increases from 1.0 to 2.0, radiation flux at the Top of Atmosphere changes from − 60 to − 80 W/m 2 in the Double dust experiment. The Surface Long-wave Radiation Flux of 8.0 W/m 2 remains unchanged in both cases. The Outgoing Long-wave Radiation (OLR) flux changes from 2.0 to 4.0 W/m 2 indicating reduction in convective formation and as well as decrease in precipitation of 2 mm/day in the Sahel, while precipitation increases from 2 to 4 mm/day in the Guinea coast region. There was also strengthening of TEJ core and weakening of AEJ above average as dust concentration increases in some parts of the region during the monsoon period. The air temperature increases from 22.5 to 38.5 °C in both cases from coastal area to Sahelian region of West Africa. It was concluded that substantial amount of dust concentration in the atmosphere could trigger and increase radiative forcing of aerosols thereby sensitive to monsoon variability and results in enhancement of precipitation amount in the Guinea coast and reduction of precipitation amount in the Sahel region of West Africa. Meanwhile, there is need to inquire more into difference aerosol concentration per specie that can trigger or increase radiative forcing in the atmosphere.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This paper identifies fundamental issues which prevent the effective uptake of climate information services in Nigeria. We propose solutions which involve the extension of short-range (1 to 5 days) forecasts beyond that of medium-range (7 to 15 days) timescales through the operational use of current forecast data as well as improve collaboration and communication with forecast users. Using newly available data to provide seamless operational forecasts from short-term to sub-seasonal timescales, we examine evidence to determine if effective demand-led sub-seasonal-to-seasonal (S2S) climate forecasts can be co-produced. This evidence involves: itemization of forecast products delivered to stakeholders, with their development methodology; enumeration of inferences of forecast products and their influences on decisions taken by stakeholders; user-focused discussions of improvements on co-produced products; and the methods of evaluating the performance of the forecast products.We find that extending the production pipeline of short-range forecast timescales beyond the medium-range, such that the medium-range forecast timescales can be fed into existing tools for applying short-range forecasts, assisted in mitigating the risks of sub-seasonal climate variability on socio-economic activities in Nigeria. We also find that enhancing of collaboration and communication channels between the producers and the forecast product users helps to: enhance the development of user-tailored impact-based forecasts; increases users' trusts in the forecasts; and, seamlessly improves forecast evaluations. In general, these measures lead to more smooth delivery and increase in uptake of climate information services in Nigeria.

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