Mineral dust aerosols play an important role in the climate system. Coupled climate‐aerosol models are an important tool with which to quantify dust fluxes and the associated climate impact. Over the last decade or more, numerous models have been developed, both global and regional, but to date, there have been few attempts to compare the performance of these models. In this paper a comparison of five regional atmospheric models with dust modules is made, in terms of their simulation of meteorology, dust emission and transport. The intercomparison focuses on a 3‐day dust event over the Bodélé depression in northern Chad, the world's single most important dust source. Simulations are compared to satellite data and in situ observations from the Bodélé Dust Experiment (BoDEx 2005). Overall, the models reproduce many of the key features of the meteorology and the large dust plumes that occur over the study domain. However, there is at least an order of magnitude range in model estimates of key quantities including dust concentration, dust burden, dust flux, and aerosol optical thickness. As such, there remains considerable uncertainty in model estimates of the dust cycle and its interaction with climate. This paper discusses the issues associated with partitioning various sources of model uncertainty.

Dust plays a vital role in climate and biophysical feedbacks in the Earth system. One source of dust, the Bodélé Depression in Chad, is estimated to produce about half the mineral aerosols emitted from the Sahara, which is the world's largest source. By using a variety of new remote sensing data, regional modeling, trajectory models, chemical analyses of dust, and future climate simulations, we investigate the current and past sensitivity of the Bodélé. We show that minor adjustments to small features of the atmospheric circulation, such as the Bodélé Low-Level Jet, could profoundly alter the behavior of this feature. Dust production during the mid-Holocene ceased completely from this key source region. Although subject to a great deal of uncertainty, some simulations of the 21st century indicate the potential for a substantial increase in dust production by the end of the century in comparison with current values.

Simultaneous measurements of saltation, wind speed, and rainfall performed in Niger before, during, and after 18 rain events are used to investigate how rain events affect wind erosion in the Sahel. The results show that the inhibition of saltation is rapid but progressive after the beginning of a rain event. The decrease of sand transport during the rain event is better linked to the time elapsed from the beginning of the rain event rather than to the cumulative rainfall. In the Sahel, after a rain event, less than 12 h is necessary to almost fully restore the sand transport potential. Our results suggest that assuming that no sand transport and dust emission occur during the 12 h following the end of a rain event could be a reasonable alternative to existing parameterizations of the influence of soil moisture on the wind erosion threshold, at least for the Sahelian conditions.

In spite of their importance for the modeling of the atmospheric cycle of mineral dust, measurements of the intensity and size distribution of the dust emission flux produced by wind erosion in natural conditions remain rare. During the WIND‐O‐V's (WIND erOsion in presence of sparse Vegetation) 2017 experiment, eight major erosion events having occurred on a sandy flat field of southern Tunisia were documented. Consistent with the small size (90 μm) of the erodible sand grains and the low aerodynamic roughness length (Z₀ < 0.079 cm), the threshold for wind erosion was low (u_*t = 22 cm/s). The classical gradient method was applied to assess the size‐resolved vertical dust flux, and the stability of the atmosphere quantified by the means of the Richardson number (Ri) as well as of its shear stress (u_*) and thermal gradient (∂θ/∂z) components. The vertical dust flux increased with u_* following a power law but the number size distribution of the dust flux was found to be significantly richer in submicron particles in thermally unstable than in stable periods. This challenges the usual assumption that, independently of their size, the particles smaller than 10 μm follow equally the movements of the air masses in which they are embedded and that the thermal stratification of the surface layer does not affect the size distribution of the surface flux when measured a few meters above the ground. Finally, we propose a simple empirical method for taking this influence of the thermal instability into account.