Laboratory investigation of the radiative properties of mineral dust across the solar and terrestrial spectrum: key achievements and future directions

Coarse mineral dust aerosols originating from arid and semi-arid regions worldwide constitute one of the dominant tropospheric aerosol species by mass. Mineral dust both absorbs and scatters solar and terrestrial radiation, thereby influencing the radiance spectrum at the surface and at the top of the atmosphere, as well as the atmospheric heating rate. Dust is a key, yet still highly uncertain, contributor to both historical and contemporary climate change.

Modelling the interaction of dust with atmospheric radiation remains challenging because dust absorption and scattering properties, represented by the complex refractive index, depend on mineralogical composition – which varies with the emission source – and on particle size distribution, which evolves during transport. Climate models and remote-sensing retrievals therefore require accurate, regionally dependent information to improve dust representation and reduce uncertainties in radiative effect estimates.

Laboratory investigation has proven to be a powerful approach for unravelling the optical properties of mineral dust across the solar and terrestrial infrared spectrum. Original experiments based on realistic aerosols generated from natural soils have provided important new insights into the optical properties of global mineral dust in the solar and thermal infrared spectral ranges, as well as their variability with particle composition and during transport. These results have motivated the modelling and remote-sensing communities to revisit dust representation in models, leading to new evaluations of the dust direct radiative effect and its associated uncertainty, as well as to the development of innovative remote-sensing products. Current research is now extending the investigated spectral range toward the far infrared and to emerging source regions, for which knowledge of dust–radiation interactions remains very limited.

This presentation highlights key results and open scientific questions that have driven recent research on the radiative properties of mineral dust, and outlines perspectives for future studies.