Seasonal Predictions and Monitoring for Sahel Region

2007 ◽  
pp. 49-56
Author(s):  
G. Maracchi ◽  
V. Capecchi ◽  
A. Crisci ◽  
F. Piani
Keyword(s):  
Sahel Region

Guide to Risk Factors for Elections in the G5 Sahel Region: Factors External to the Electoral Process

2020 ◽  
Author(s):  
Sead Alihodzic ◽  
Maurice Mboula Jean-Claude Didier Enguélégué ◽  
Idayat Hassan ◽  
Robin Watts
Keyword(s):  
Risk Factors ◽  
Electoral Process ◽  
Sahel Region

scholarly journals Understanding the variability of the rainfall dipole in West Africa using the EC-Earth last millennium simulation

2021 ◽  
Author(s):  
Qiong Zhang ◽  
Ellen Berntell ◽  
Qiang Li ◽  
Fredrik Charpentier Ljungqvist
Keyword(s):  
West Africa ◽  
Model Simulation ◽  
Rainfall Variability ◽  
Low Pressure ◽  
Last Millennium ◽  
Tropical Atlantic ◽  
Gulf Of Guinea ◽  
Dipole Pattern ◽  
Sahel Region ◽  
Heat Low

AbstractThere is a well-known mode of rainfall variability associating opposite hydrological conditions over the Sahel region and the Gulf of Guinea, forming a dipole pattern. Previous meteorological observations show that the dipole pattern varies at interannual timescales. Using an EC-Earth climate model simulation for last millennium (850–1850 CE), we investigate the rainfall variability in West Africa over longer timescales. The 1000-year-long simulation data show that this rainfall dipole presents at decadal to multidecadal and centennial variability and long-term trend. Using the singular value decomposition (SVD) analysis, we identified that the rainfall dipole present in the first SVD mode with 60% explained variance and associated with the variabilities in tropical Atlantic sea surface temperature (SST). The second SVD mode shows a monopole rainfall variability pattern centred over the Sahel, associated with the extra-tropical Atlantic SST variability. We conclude that the rainfall dipole-like pattern is a natural variability mode originated from the local ocean–atmosphere-land coupling in the tropical Atlantic basin. The warm SST anomalies in the equatorial Atlantic Ocean favour an anomalous low pressure at the tropics. This low pressure weakens the meridional pressure gradient between the Saharan Heat Low and the tropical Atlantic. It leads to anomalous northeasterly, reduces the southwesterly moisture flux into the Sahel and confines the Gulf of Guinea's moisture convergence. The influence from extra-tropical climate variability, such as Atlantic multidecadal oscillation, tends to modify the rainfall dipole pattern to a monopole pattern from the Gulf of Guinea to Sahara through influencing the Sahara heat low. External forcing—such as orbital forcing, solar radiation, volcanic and land-use—can amplify/dampen the dipole mode through thermal forcing and atmosphere dynamical feedback.

User fees removal and community-based management of undernutrition in Burkina Faso: what effects on children’s nutritional status?

2021 ◽  
pp. 1-12
Author(s):  
David Y Zombré ◽  
Manuela De Allegri ◽  
Valéry Ridde ◽  
Kate Zinszer
Keyword(s):  
Burkina Faso ◽  
Household Survey ◽  
Community Level ◽  
User Fees ◽  
Nutrition Status ◽  
Control Group ◽  
Community Based ◽  
Sahel Region ◽  
Intervention District ◽  
Children Under 5

Abstract Objective: To examine the effect of an intervention combining user fees removal with community-based management of undernutrition on the nutrition status in children under 5 years of age in Burkina Faso. Design: The study was a non-equivalent control group post-test-only design based on household survey data collected 4 years after the intervention onset in the intervention and comparison districts. Additionally, we used propensity score weighting to achieve balance on covariates between the two districts, followed by logistic multilevel modelling. Setting: Two health districts in the Sahel region. Participants: Totally, 1116 children under 5 years of age residing in 41 intervention communities and 1305 from 51 control communities. Results: When comparing children living in the intervention district to children living in a non-intervention district, we determined no differences in terms of stunting (OR = 1·13; 95 % CI 0·83, 1·54) and wasting (OR = 1·21; 95 % CI 0·90, 1·64), nor in severely wasted (OR = 1·27; 95 % CI 0·79, 2·04) and severely stunted (OR = 0·99; 95 % CI 0·76, 1·26). However, we determined that 3 % of the variance of wasting (95 % CI 1·25, 10·42) and 9·4 % of the variance of stunting (95 % CI 6·45, 13·38) were due to systematic differences between communities of residence. The presence of the intervention in the communities explained 2 % of the community-level variance of stunting and 3 % of the community-level variance of wasting. Conclusions: With the scaling-up of the national free health policy in Africa, we stress the need for rigorous evaluations and the means to measure expected changes in order to better inform health interventions.

Multi-model ensemble projections of soil moisture drought over North Africa and the Sahel region under 1.5, 2, and 3 °C global warming

2021 ◽  
Vol 167 (3-4) ◽  
Author(s):  
Ahmed Elkouk ◽  
Zine El Abidine El Morjani ◽  
Yadu Pokhrel ◽  
Abdelghani Chehbouni ◽  
Abdelfattah Sifeddine ◽  
...  
Keyword(s):  
Global Warming ◽  
Soil Moisture ◽  
North Africa ◽  
Model Ensemble ◽  
Sahel Region ◽  
Ensemble Projections

scholarly journals Impact of Desert Dust Radiative Forcing on Sahel Precipitation: Relative Importance of Dust Compared to Sea Surface Temperature Variations, Vegetation Changes, and Greenhouse Gas Warming

2007 ◽  
Vol 20 (8) ◽  
pp. 1445-1467 ◽  
Author(s):  
Masaru Yoshioka ◽  
Natalie M. Mahowald ◽  
Andrew J. Conley ◽  
William D. Collins ◽  
David W. Fillmore ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Africa ◽  
Radiative Forcing ◽  
Sea Surface ◽  
Desert Dust ◽  
Direct Radiative Forcing ◽  
Sahel Region ◽  
Precipitation Reduction ◽  
Sahel Precipitation

Abstract The role of direct radiative forcing of desert dust aerosol in the change from wet to dry climate observed in the African Sahel region in the last half of the twentieth century is investigated using simulations with an atmospheric general circulation model. The model simulations are conducted either forced by the observed sea surface temperature (SST) or coupled with the interactive SST using the Slab Ocean Model (SOM). The simulation model uses dust that is less absorbing in the solar wavelengths and has larger particle sizes than other simulation studies. As a result, simulations show less shortwave absorption within the atmosphere and larger longwave radiative forcing by dust. Simulations using SOM show reduced precipitation over the intertropical convergence zone (ITCZ) including the Sahel region and increased precipitation south of the ITCZ when dust radiative forcing is included. In SST-forced simulations, on the other hand, significant precipitation changes are restricted to over North Africa. These changes are considered to be due to the cooling of global tropical oceans as well as the cooling of the troposphere over North Africa in response to dust radiative forcing. The model simulation of dust cannot capture the magnitude of the observed increase of desert dust when allowing dust to respond to changes in simulated climate, even including changes in vegetation, similar to previous studies. If the model is forced to capture observed changes in desert dust, the direct radiative forcing by the increase of North African dust can explain up to 30% of the observed precipitation reduction in the Sahel between wet and dry periods. A large part of this effect comes through atmospheric forcing of dust, and dust forcing on the Atlantic Ocean SST appears to have a smaller impact. The changes in the North and South Atlantic SSTs may account for up to 50% of the Sahel precipitation reduction. Vegetation loss in the Sahel region may explain about 10% of the observed drying, but this effect is statistically insignificant because of the small number of years in the simulation. Greenhouse gas warming seems to have an impact to increase Sahel precipitation that is opposite to the observed change. Although the estimated values of impacts are likely to be model dependent, analyses suggest the importance of direct radiative forcing of dust and feedbacks in modulating Sahel precipitation.

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