Multi-Decadal Variability and Future Changes in Precipitation over Southern Africa

Sian, Kenny Thiam Choy Lim Kam; Wang, Jianhong; Ayugi, Brian; Nooni, Isaac Kwesi; Ongoma, Victor

doi:10.3390/atmos12060742

Cited by 47 publications

(26 citation statements)

References 79 publications

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“…The findings for the seasonal cycle for the historical period were unimodal and close to the cycle south of the equator. This result is consistent with the CMIP6 P seasonality found in Southern Africa by [73]. However, the future climate presented an opposite seasonal cycle for all the SSP-RCPs (Figure 3).…”

Section: Discussionsupporting

confidence: 89%

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Future Changes in Simulated Evapotranspiration across Continental Africa Based on CMIP6 CNRM-CM6

Nooni

Hagan

Wang

et al. 2021

IJERPH

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The main goal of this study was to assess the interannual variations and spatial patterns of projected changes in simulated evapotranspiration (ET) in the 21st century over continental Africa based on the latest Shared Socioeconomic Pathways and the Representative Concentration Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) provided by the France Centre National de Recherches Météorologiques (CNRM-CM) model in the Sixth Phase of Coupled Model Intercomparison Project (CMIP6) framework. The projected spatial and temporal changes were computed for three time slices: 2020–2039 (near future), 2040–2069 (mid-century), and 2080–2099 (end-of-the-century), relative to the baseline period (1995–2014). The results show that the spatial pattern of the projected ET was not uniform and varied across the climate region and under the SSP-RCPs scenarios. Although the trends varied, they were statistically significant for all SSP-RCPs. The SSP5-8.5 and SSP3-7.0 projected higher ET seasonality than SSP1-2.6 and SSP2-4.5. In general, we suggest the need for modelers and forecasters to pay more attention to changes in the simulated ET and their impact on extreme events. The findings provide useful information for water resources managers to develop specific measures to mitigate extreme events in the regions most affected by possible changes in the region’s climate. However, readers are advised to treat the results with caution as they are based on a single GCM model. Further research on multi-model ensembles (as more models’ outputs become available) and possible key drivers may provide additional information on CMIP6 ET projections in the region.

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Section: Discussionsupporting

confidence: 89%

“…The humid-tropical zones (along with the Guinean coast) and the interior of the Cameroonian, Kenyan, and Ethiopian Highlands provided a comparatively similar mean ET. The ET pattern recorded is consistent with CMIP6 P patterns found in East Africa [77], North Africa [78] and Southern Africa [73].…”

Section: Discussionsupporting

confidence: 85%

Future Changes in Simulated Evapotranspiration across Continental Africa Based on CMIP6 CNRM-CM6

Nooni

Hagan

Wang

et al. 2021

IJERPH

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“…The two main projections utilized are drawn from Tier 1 ScenarioMIP: SSP2-4.5 and SSP5-8.5. Following the recommendations of previous studies (e.g., [57,[81][82][83][84][85]), this employs MME of CMIP6 for projection of extreme events over the study area. Many studies have remarked on the robustness of MME as compared to individual models due to cancellation of intermodel biases [59].…”

Section: Discussionmentioning

confidence: 99%

“…Simultaneously, the OND season shows likely intensification of PRCPTOT, R95 p, and CWD over Uganda and most parts of Kenya, while reduction is observed over the Tanzania region (Figures 5 and 6). Presence of complex topography has considerable influence on the variation of extreme events and impacted regions [66,83]. For instance, the presence of large inland water bodies-i.e., Lake Victoria, which is the largest freshwater lake in Africa and second in the world, covering about 68,000 km 2 and bordering three countries, Uganda (45%), Tanzania (49%), and Kenya (6%)-have a significant influence on the incidences of extreme events [84].…”

Section: Discussionmentioning

confidence: 99%

Future Changes in Precipitation Extremes over East Africa Based on CMIP6 Models

Ayugi

Dike

Ngoma

et al. 2021

Water

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This paper presents an analysis of projected precipitation extremes over the East African region. The study employs six indices defined by the Expert Team on Climate Change Detection Indices to evaluate extreme precipitation. Observed datasets and Coupled Model Intercomparison Project Phase six (CMIP6) simulations are employed to assess the changes during the two main rainfall seasons: March to May (MAM) and October to December (OND). The results show an increase in consecutive dry days (CDD) and decrease in consecutive wet days (CWD) towards the end of the 21st century (2081–2100) relative to the baseline period (1995–2014) in both seasons. Moreover, simple daily intensity (SDII), very wet days (R95 p), very heavy precipitation >20 mm (R20 mm), and total wet-day precipitation (PRCPTOT) demonstrate significant changes during OND compared to the MAM season. The spatial variation for extreme incidences shows likely intensification over Uganda and most parts of Kenya, while a reduction is observed over the Tanzania region. The increase in projected extremes may pose a serious threat to the sustainability of societal infrastructure and ecosystem wellbeing. The results from these analyses present an opportunity to understand the emergence of extreme events and the capability of model outputs from CMIP6 in estimating the projected changes. More studies are recommended to examine the underlying physical features modulating the occurrence of extreme incidences projected for relevant policies.

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“…More recently, CMIP6 simulations have been investigated in terms of mean precipitation change at continental scale (Almazroui et al 2020) and for southern Africa (Sian 2021), and by extreme events over East Africa (Ayugi et al 2021a). In addition, Moon and Ha (2020) and Ukkola et al (2020) investigated future characteristics of (global) monsoon precipitation and meteorological droughts, respectively.…”

Section: Introductionmentioning

confidence: 99%

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

et al. 2021

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We provide an assessment of future daily characteristics of African precipitation by explicitly comparing the results of large ensembles of global (CMIP5, CMIP6) and regional (CORDEX, CORE) climate models, specifically highlighting the similarities and inconsistencies between them. Results for seasonal mean precipitation are not always consistent amongst ensembles: in particular, global models tend to project a wetter future compared to regional models, especially over the Eastern Sahel, Central and East Africa. However, results for other precipitation characteristics are more consistent. In general, all ensembles project an increase in maximum precipitation intensity during the wet season over all regions and emission scenarios (except the West Sahel for CORE) and a decrease in precipitation frequency (under the Representative Concentration Pathways RCP8.5) especially over the West Sahel, the Atlas region, southern central Africa, East Africa and southern Africa. Depending on the season, the length of dry spells is projected to increase consistently by all ensembles and for most (if not all) models over southern Africa, the Ethiopian highlands and the Atlas region. Discrepancies exist between global and regional models on the projected change in precipitation characteristics over specific regions and seasons. For instance, over the Eastern Sahel in July–August most global models show an increase in precipitation frequency but regional models project a robust decrease. Global and regional models also project an opposite sign in the change of the length of dry spells. CORE results show a marked drying over the regions affected by the West Africa monsoon throughout the year, accompanied by a decrease in mean precipitation intensity between May and July that is not present in the other ensembles. This enhanced drying may be related to specific physical mechanisms that are better resolved by the higher resolution models and highlights the importance of a process-based evaluation of the mechanisms controlling precipitation over the region.

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Multi-Decadal Variability and Future Changes in Precipitation over Southern Africa

Cited by 47 publications

References 79 publications

Future Changes in Simulated Evapotranspiration across Continental Africa Based on CMIP6 CNRM-CM6

Future Changes in Simulated Evapotranspiration across Continental Africa Based on CMIP6 CNRM-CM6

Future Changes in Precipitation Extremes over East Africa Based on CMIP6 Models

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

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