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Vendredi 8 avril 2016 à 11h00
Université Pierre et Marie Curie
Salle de réunion 411 du LATMOS, tour 45-46, 4ème ètage

The Mid-Holocene West African Monsoon Modulated by Land Surface Cover and Saharan Dust

Gabriele Messori, UK Met Office

The West African Monsoon plays a fundamental role in the socio-economic stability of a large part of Africa, and changes in the monsoon’s location and intensity can have a severe impact on the local populations. Climate models struggle to successfully simulate both the present-day and historical monsoon variability, such as the monsoon’s intensification and northward extension during the mid-Holocene (6000 yrs BP). Understanding the reasons behind this shortcoming is an essential step to improve projections of the future monsoons.
This presentation discusses whether the discrepancies between model simulations and paleo-data for the mid-Holocene can be attributed to prescribed initial conditions, with a focus on the role of land cover and dust loading in the atmosphere. It is found that land cover has a profound impact on the hydrological cycle of North Africa, with dust emission triggering complex feedback loops. The monsoon’s duration, intensity and geographical extent are all sensitive to the combined action of land cover and dust loading changes over the Sahel and Sahara. Since both dust loadings and land cover are expected to change in the future, an assessment of their impacts on precipitation is extremely valuable for our understanding of both the past and future climate of North Africa.