Journal Articles

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12504/83

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Browsing Journal Articles by Subject "Africa"

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    Drought severity across Africa: a comparative analysis of multi-source precipitation datasets
    (Springer, 2024-04) Lim Kam Sian, Kenny Thiam Choy; Onyutha, Charles; Ayugi, Brian Odhiambo; Njouenwet, Ibrahim; Ongoma, Victor
    An accurate analysis of climate extremes is essential for impact assessment and devising appropriate adaptation measures. There is an urgent need to assess precipitation products in capturing the increasing occurrence of climate extremes. This study evaluates the ability of 20 observational datasets, including gauge-based, satellite-based and reanalyses, in representing different drought severity (moderate, severe and extreme drought) over Africa and its nine sub-regions at varying time scales (3-, 6- and 12-months) during 1983–2014. Drought is represented using the Standardized Precipitation Index (SPI). The results demonstrate that while most datasets are suitable for drought studies over the continent, the African Rainfall Climatology version 2 (ARC2) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks Climate Data Records (PERSIANN_CDR_v1r1) are less fitted for such investigations. Moreover, regions such as the Sahara (SAH), Central Africa (CAF) and North Eastern Africa (NEAF) show a larger disparity among the datasets, requiring more caution when selecting a dataset for use in such areas. Generally, the datasets present low agreement toward the lower end of the range (5–30%) because the individual datasets estimate varying drought severities at different grids and months. This is observed in the coefficient of variation of 20–25% of the datasets falling outside the ± 1 standard deviation range. Therefore, using an ensemble to represent the datasets remains an indispensable tool. The datasets present better agreement in the timing of drought events than the spatial distribution. The findings provide valuable insights into the complexity of drought assessment using diverse precipitation datasets. Furthermore, the results highlight the significance of considering spatial and temporal dimensions, as datasets may capture drought events at varying locations and times, revealing subtle variations in drought impact.
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    Multi-Country-multi-city characterisation of heat stress and exposure in Africa
    (International Journal of Climatology, 2026-04-21) Morakinyo, Tobi Eniolu; Adeyeri, Oluwafemi E.; Daramola, Mojolaoluwa Toluwalase; Vishal, Bobde; Ishola, Kazeem Abiodun; Obe, Oluwafemi Benjamin; Eresanya, Emmanuel Olaoluwa; Akinsanola, Akintomide Afolayan; Onyutha, Charles; Ayugi, Brian Odhiambo; Nying'uro, Patricia
    This study presents the first continent-wide assessment of long-term (1974–2023) summer heat stress in Africa using the Universal Thermal Climate Index (UTCI) derived from ERA5-HEAT reanalysis datasets. Employing a grid-specific definition of summer, we analysed UTCI trends across spatial (continental to city scale) and temporal (decadal to hourly) dimensions. While annual UTCI anomalies range 0.2°C–1.6°C, substantial intensification emerges at finer scales. The frequency, duration and spatial extent of ‘very strong’ (38°C–46°C) and ‘extreme’ (≥46°C) heat stress have increased markedly, particularly, in the Sahel. Heatstressed hours (UTCI>32°C) rose by 2%–25% across most countries, with extreme events doubling in 3–5 and 6–8days episodes. City-level analyses reveal escalating risks in large urban centres like Cairo, Lagos and Kano. As climate projections indicate further intensification, the findings underscore the urgent need for targeted heat-health adaptation and early warning systems to protect vulnerable populations across the continent.