Enhanced prediction methods for the onset and cessation dates of the rainy season over the Guinea Savanna, Nigeria

Ezeh, Christopher Uche; Ekwezuo, Chukwudi Samuel; Emeribe, Chukwudi Nnaemeka; Butu, Ali Williams

doi:10.1007/s12517-021-06507-7

Cited by 2 publications

(2 citation statements)

References 22 publications

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“…In most cases, these definitions and thresholds produce different wet/dry days and spells even when applied to the same observation or gridded dataset 27 . The first and most used methods in the literature are those that apply threshold values on Total rainfall amount 17 , 54 – 57 , Fraction of evapotranspiration 58 , Walter method 59 , Number of rainy days and spell lengths 27 . All these methods have limitations regarding a number of rainy days within the threshold of total rainfall amount, seasonal extremes indices and probability of exceeding defined wet days and dry spells.…”

Section: Methodsmentioning

confidence: 99%

Observed changes in wet days and dry spells over the IGAD region of eastern Africa

Omay,

Muthama,

Oludhe

et al. 2023

Sci Rep

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Changes in wet and dry patterns have an impact on rain-fed agriculture, crop productivity, and food security in Eastern Africa. The purpose of this research is to look into the changes in wet days and dry periods within the Intergovernmental Authority on Development (IGAD) region. Climate Hazards Group Infrared Precipitation with Station Data (CHIRPS) and Multi Models Ensembles (MME) of 10 historical simulations and projections from Coupled Model Intercomparison Project (CMIP6) models were employed as the data source. Several statistical approaches, as well as wet and dry spell thresholds, were used to calculate patterns of change in wet and dry spells on a decadal (10-year), 20, 30, and 41-year time scale. The results show the region exhibits decrease a decrease in the number of wet days and protracted dry spells in the 1980s, followed by an extraordinary (exceptional) increase in wet days in the subsequent decades (2011–2020) during March–May (MAM), June–September (JJAS), and October-December (OND). In Kenya, Somalia, southeastern Ethiopia, Eritrea, and Djibouti, the probability of surpassing 7, 14, 21, 28 days (1, 2, 3, 4 spells) was less than 5%. Furthermore, floods in 1997, 2018, 2019, and 2020, as well as droughts in 1983, 1984, 1985, and 2021, were triggered by an increase or decrease in the number of wet days and dry spells over most of the region. The number of wet days is projected to decrease by 10–20% during the MAM season across Sudan, South Sudan, and central and northern Ethiopia, JJAS is projected to increase by 30–50% across central and northern Sudan. However, during the OND season, increases are projected over Uganda, Ethiopia, and Kenya under three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5) scenarios. These findings contributed to the advancement of scientific knowledge in the IGAD region, as well as decision-making, food security, and the development of adaptation and mitigation strategies. We encourage rain-fed agriculture, crop variety planning, and irrigation supplement.

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Section: Methodsmentioning

confidence: 99%

Observed changes in wet days and dry spells over the IGAD region of eastern Africa

Omay,

Muthama,

Oludhe

et al. 2023

Sci Rep

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“…where ORD is the date of the onset/retreat of the rainy season, DM is the number of days in the month that contain the rain amount greater than or equal to (Tr * 0.083), and Ac is the rains accumulated in the months preceding the month that has the value of (Tr * 0.083), Tr is the total annual rainfall, and RM is the total amount of rain in the very month that has (Tr x 0.083) (Anyadike, 1993). The formula is applied in reverse order by accumulating rainfall total backward from the end of the year to obtain the real date of retreat (Anyadike, 1993;Ezeh et al, 2021).…”

Section: Historical Climate Datamentioning

confidence: 99%

Associating farmers’ perception of climate change and variability with historical climate data

2022

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The farmers? perceptions of climate change (CC) and variability in Okpuje were assessed and compared with historical climate data. They perceive an occurrence of change that affects their farm activities, but lack the scientific understanding of this change. While some do not know what causes the change, others attribute it to God?s vengeance. The perceptions of rising temperature and delay in the onset of the rainy season are corroborated by the analysis of the climate data. The temperature is significantly rising and it increased at the rate of 0.14?C per decade between 1960 and 2019. The rainfall decreased at the rate of 8.5 mm per decade. The rainy season tends toward late-onset and early cessation dates. However, the perception of increasing rainfall in the area was not upheld by the trend analysis of the rainfall data. The difference might be due to high variability in rainfall in space and time. The high rainfall recorded lately might have posed difficulty for the human memory as closer events are remembered easier than distant events and hence can be unravelled via a scientific approach. Nevertheless, since perception shapes adaptation, the people?s indigenous perceptions and experiences should form part of intervention measures and policies for CC adaptation to command greater participation and wider acceptance. Thus, farmers? perceptions provide vital information but would be more reliable if integrated with scientific data analysis for policy and decision-makers in CC science, implying that none of them should be relegated but integrated.

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Enhanced prediction methods for the onset and cessation dates of the rainy season over the Guinea Savanna, Nigeria

Cited by 2 publications

References 22 publications

Observed changes in wet days and dry spells over the IGAD region of eastern Africa

Observed changes in wet days and dry spells over the IGAD region of eastern Africa

Associating farmers’ perception of climate change and variability with historical climate data

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