CANCELED 25.11.25 BOKU-Met Seminar
Mineral dust aerosol plays a key role in Earth's radiation budget by absorbing and scattering radiation. The single scattering albedo (SSA), a parameter governing dust radiation interaction, varies with dust particle size, shape, and mineralogical composition. Emitted primarily from arid and semi-arid regions, dust represents a major component of the global aerosol burden and remains a significant source of uncertainty in weather and climate models, largely due to challenges in accurately characterizing its optical and microphysical properties.
Dust models typically assume a globally homogeneous composition for the calculation of dust optical properties. However, minerals present in dust aerosols vary regionally and with particle size, depending on the parent soil mineralogical composition. Among others, uncertainties remain in the abundance of iron oxides in soils and at emission, and their absorptive properties (i.e., imaginary part of the refractive index).
Here, with a set of controlled experiments conducted with the Multiscale Online Non-hydrostatic AtmospheRe CHemistry model (MONARCH), we aim at disentangling the impact of regional and size variations of dust mineralogy in single scattering albedo and its direct radiative effect. We also assess the sensitivity of our results to different soil mineralogy information, including the recent observationally constrained EMIT dataset, and to uncertainties in the iron oxides refractive indexes. We conducted a seasonal and annual analysis of global dust transport, optical properties, and direct radiative effect using the Rapid Radiative Transfer Model for GCMs (RRTMG).