Progress and Challenges in Mineral Dust Modelling

A public lecture was given on Monday, 27 February 2017 by Dr Benoit Laurent, Associate Professor in Chemistry, Atmospheric and Environmental Sciences at the University Paris Diderot. Dr Laurent addressed developments in mineral dust modelling, concentrating on northern and southern desert areas, recent results and ongoing research in the area of atmospheric mineral dust.

Atmospheric mineral dust is emitted from the arid and semi-arid areas, produced by Aeolian (sand) erosion.  Surface-Atmosphere interactions control the occurrence and the intensity of dust emissions.  Dust emissions and deposition are controlled by sporadic processes leading to a very high variability of the atmospheric dust load. The dust is transported over long distances forming dry deposition of dust or else wet dust deposition (precipitation effect). When the wind speed is strong enough over a surface not totally protected by vegetation, stones or pebbles, some grains constituting the superficial layer of the soil begin to move, causing a threshold phenomenon.  The saltating grains mobilized by wind fall down the surface, a part of their kinetic energy is transferred to soil aggregates which disrupt, allowing finer particles to be emitted into the atmosphere.

Mineral dust emissions are the main source of tropospheric aerosols in mass.  They have a radiative, socio-economic and human health impacts.  When mineral dust is emitted in oligotrophic oceanic surface water areas, then elements such as Iron, Phosphorus, Nitrogen and Silicon are added to water.

To evaluate the impacts of dust on the environment the atmospheric concentrations which are controlled by the balance between emission and deposition processes need to be measured and modelled correctly. There are no direct and quantitative observations of mineral dust emissions available at such temporal and spatial scales, and this is a challenge.  Dr Laurent is involved in the AEROCLO-sA research, with the main objective of simulating atmospheric aerosol concentrations and investigating the radiative effect (direct and semi-direct) and biogeochemical impact at regional/continental scales in Namibia.

 

Selma Udjombala

Communication intern

Faculty of Natural Resources and Spatial Sciences

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