ROLE OF THE HOGGAR MASSIF ON THE WEST AFRICAN MONSOON ONSET

It has been observed that the West African monsoon onset is concomitant with the enhancement of the Saharan heat low. We show here through a combined diagnostic and modeling study a possible interaction between northern Africa orography and the deepening of the Saharan heat low at the time of the monsoon onset. The amplification of an anticyclonic circulation above and north of the Hoggar massif leads to an increase and a southeasterly-northeasterly rotation of the wind ahead of the Hoggar which contribute to an increased leeward-trough effect enhancing the Saharan heat low. The Atlas does not play any role during the monsoon onset but contributes to the mean climatological location of the Saharan heat low

The impact of future climate change and potential adaptation methods on Maize yields in West Africa

International audienceMaize (Zea mays) is one of the staple crops of West Africa and is therefore of high importance with regard to future food security. The ability of West Africa to produce enough food is critical as the population is expected to increase well into the twenty-first century. In this study, a process-based crop model is used to project maize yields in Africa for global temperatures 2 K and 4 K above the preindustrial control. This study investigates how yields and crop failure rates are influenced by climate change and the efficacy of adaptation methods to mitigate the effects of climate change. To account for the uncertainties in future climate projections, multiple model runs have been performed at specific warming levels of + 2 K and + 4 K to give a better estimate of future crop yields. Under a warming of + 2 K, the maize yield is projected to reduce by 5.9% with an increase in both mild and severe crop failure rates. Mild and severe crop failures are yields 1 and 1.5 standard deviations below the observed yield. At a warming of + 4 K, the results show a yield reduction of 37% and severe crop failures which previously only occurred once in 19.7 years are expected to happen every 2.5 years. Crops simulated with a resistance to high temperature stress show an increase in yields in all climate conditions compared to unadapted crops; however, they still experience more crop failures than the unadapted crop in the control climate

Vacancy clustering and diffusion in silicon: Kinetic lattice Monte Carlo simulations

Diffusion and clustering of lattice vacancies in silicon as a function of temperature, concentration, and interaction range are investigated by Kinetic Lattice Monte Carlo simulations. It is found that higher temperatures lead to larger clusters with shorter lifetimes on average, which grow by attracting free vacancies, while clusters at lower temperatures grow by aggregation of smaller clusters. Long interaction ranges produce enhanced diffusivity and fewer clusters. Greater vacancy concentrations lead to more clusters, with fewer free vacancies, but the size of the clusters is largely independent of concentration. Vacancy diffusivity is shown to obey power law behavior over time, and the exponent of this law is shown to increase with concentration, at fixed temperature, and decrease with temperature, at fixed concentration.Comment: 14 pages, 12 figures. To appear in Physical Review