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Abstract. In this paper, spatial and temporal patterns of changes in extreme temperatures are investigated using 10 meteorological stations data for the period 1950–2018 in the Blue Nile basin. Monthly temperature data for the basin were used in the study. Long-term trends in the Blue Nile Basin annual and monthly temperatures were investigated. The statistical significance of the trend is calculated by applying the Mann-Kendall (MK) test. The analysis of data was performed using the coefficient of variance, anomaly index. The results showed that the annual maximum and minimum temperature is increasing significantly with a magnitude of 0.037° and 0.025 °C per decade respectively in the period from 1950–2018. The result of the Mann-Kendall analysis test revealed a marked increase in mean maximum and minimum temperatures trend over time significantly during the study period (the minimum temperature rate is more evident than the maximum). The long-term anomalies of mean annual minimum temperature revealed the inter-annual variability while the trend after 1977 was higher than the long-term average that is proof of the warming trend existence since the last two decades of the 20th century.

The relation between sunspots and rainfall patterns is still obscure in Africa, especially for Sudan and South Sudan. This research explores the response of rainfall to solar activity in eastern regions of Africa, with a case study in Sudan and South Sudan. Rainfall varies with time; therefore, skillful monitoring, predicting, and early warning of rainfall events is indispensable. Severe climatic events, such as droughts and floods, are critical factors in planning and managing all socioeconomic activities. Similar trends for the sunspot activity (sunspot number and sunspot groups) changes and rainfall variations for different stations in East Africa during the years 1910–2018 were not found. Correlation analysis carried out for the above period indicated a weak negative correlation between the total rainfall and the average number of sunspots over the long-term scale for selected stations in Sudan and South Sudan. The overall result of the paper indicated no significant relationship between sunspot numbers and rainfall in temporal and spatial scales in Sudan and South Sudan.

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