Probability of dry and wet spells over West Africa during the summer monsoon season

Basse, Jules; Camara, Moctar; Diba, Ibrahima; Diédhiou, Arona

doi:10.5897/sre2021.6718

Cited by 2 publications

(1 citation statement)

References 38 publications

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“…In the four subregions of West Africa (Western and Central Sahel, Sudanian zone, and Guinea Coast), dry spells lasting 2–3 days mostly occur during the rainy seasons with maximum occurrence in August in the two Sahelian and the Sudanian regions and in May–June and September over Guinea Coast with weaker occurrence during the little dry season in August (Froidurot & Diedhiou, 2017). Basse et al (2021) characterized the conditional probability of single or consecutive dry and wet days in West Africa using the first‐order Markov chain approach during the monsoon season (June to October). They reported 3 days of shorter dry spells with statistically significant decreasing trends in the Western Sahel, and 5, 7, and 10 days of longer dry spells with statistically significant downward trends over the Western and Central Sahel.…”

Section: Introductionmentioning

confidence: 99%

Rainfall extremes and trends during the little dry season in Nigeria

Adejuwon

2023

World Water Policy

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The little dry season (LDS), a phenomenon of interest in West Africa is associated with a dry spell amid the wet season and is consequential to agriculture and global food production. However, the current literature suffers a knowledge gap on rainfall extremes and trends during this period. This study examined the rainfall extremes and trends during the LDS in Nigeria using daily and monthly rainfall data from 19 synoptic stations for the period 1960 to 2020. The Kendal tau correlation, Standardized Precipitation Index (SPI), and descriptive statistics were employed for the study. The result showed the LDS reduction from the western area eastward and northward. The LDS is more intense in August than in July and is characterized by drought, ranging from mild (74.34%) to extreme (2.64%). The droughts fluctuate with wet conditions. The severe and extreme drought was mostly confined to the southwestern area. Lagos observed the highest drought occurrences, 50% of below 10‐mm rainfall and prolonged dry spells. Shaki recorded 13.73% of the total severe droughts while Osogbo recorded 43.33% of extreme drought events. The mean SPI is majorly distributed in space as mild drought and mildly wet respectively, except for a few stations where it ranged from moderate to extreme. A significant trend was negative at Bida (p ≤ .01), positive at Iseyin (p ≤ .05), Abeokuta (p ≤ .01), and Akure (p ≤ .01) in July, and Bida (p ≤ .05) in August. The LDS period is associated with hardship through prolonged dry spells and drought. This study explains the extreme rainfall and trends during the LDS to water management and suggests agricultural planning, forecasting, and mitigation of drought impacts.

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Section: Introductionmentioning

confidence: 99%

Rainfall extremes and trends during the little dry season in Nigeria

Adejuwon

2023

World Water Policy

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Projected Changes in Dry and Wet Spells over West Africa during Monsoon Season Using Markov Chain Approach

Basse,

Camara,

Diba

et al. 2024

Climate

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This study examines projected changes in dry and wet spell probabilities in West Africa during the July–August–September monsoon season using a Markov chain approach. Four simulations of regional climate models from the CORDEX-Africa program were used to analyze projected changes in intraseasonal variability. The results show an increase in the probability of having a dry day, a dry day preceding a wet day, and a dry day preceding a dry day, and a decrease in the probability of wet days in the Sahel region under anthropogenic forcing scenarios RCP4.5 and RCP8.5. The decrease in wet days is stronger in the far future and under the RCP8.5 scenario (up to −30%). The study also finds that the probability of consecutive dry days (lasting at least 7 days and 10 days) is expected to increase in western Sahel, central Sahel, and the Sudanian Area under both scenarios, with stronger increases in the RCP8.5 scenario. In contrast, a decrease is expected over the Guinea Coast, with the changes being more important under the RCP4.5. Dry spell probabilities increasing in the Sahel areas and in the northern Sudanian Area is linked to the increase in the very wet days (R95P) in the daily rainfall intensity index (SDII). These changes in dry and wet spell probabilities are important for water management decisions and risk reduction in the energy and agricultural sectors. This study also highlights the need for decision-makers to implement mitigation and adaptation policies to minimize the adverse effects of climate change.

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Probability of dry and wet spells over West Africa during the summer monsoon season

Cited by 2 publications

References 38 publications

Rainfall extremes and trends during the little dry season in Nigeria

Rainfall extremes and trends during the little dry season in Nigeria

Projected Changes in Dry and Wet Spells over West Africa during Monsoon Season Using Markov Chain Approach

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