Context and Objective Mineral dust emitted by wind erosion from arid and semi-arid zones around the globe represents more than 40% of annual emissions of tropospheric aerosols. They can then be transported at great distance from their source areas. In the atmosphere, these terrigenous particles significantly alter the Earth’s radiation balance by backscattering and absorbing solar radiation, and also by absorbing part of the telluric radiation. They can also affect cloud properties, therefore playing a major role in the climate system.

Plume of mineral aerosols on the Sahara by a storm of continental scale in March 2004 and transported on the tropical North Atlantic image :http://oceancolor.gsfc.nasa.gov/SeaWiFS/

 

Because of the magnitude of the emitted masses, these aerosols are also an important vector of material between continents and oceans. In particular, their deposition (dry or wet), in remote ocean areas constitute significant inputs in some (micro) nutrients (Fe, P…) in areas where availability is limited. Dust is therefore a key element of the functioning of some ecosystems.

 

Finally, near the emission areas, very large concentrations of these desert aerosols pose public health problems; in particular dust clouds could play a role in the development of meningitis epidemics in the Sahel zone.

 

The main objective of the “Mineral Dust Cycle’” theme is to describe and quantify emissions, deposition and the transport of desert aerosols from their sources in arid and semi-arid zones and to understand the processes that control their variability of an event scale to a multi-year scale in order to assess their radiative, bio-geochemical and health impacts.

 

These activities are conducted along four main axes :

 

 

- Axis 1 : Modeling of mineral dust emissions in arid and semi-arid areas

- Axis 2 : Long-term variability of atmospheric mineral dust content

- Axis 3 : Studies of physicochemical and optical properties of mineral aerosols

- Axis 4 : Impact of atmospheric deposition of mineral dust on marine ecosystems

 

 

Schematic representation of the cycle of mineral dust and their impact