Summary

Numerical modeling is vital to study mineral dust and its diverse impacts on the environment and human daily life. Parameterizations of dust emission in models are based on theories about the dust emission mechanisms: saltation bombardment, aggregate disintegration, and aerodynamic entrainment. Testing of such theories needs field measurements as an input. To date, most measurements do not provide enough information to allow for a determination of the dust emission mechanism and often focus on a small variety of soil and atmospheric settings. Hence, the evaluation of dust emission parameterizations has so far relied on a selective set of observations.

Here, preliminary results will be presented of a study that aims to decipher dust emission mechanisms from field measurements for a range of land-surface and atmospheric conditions. The preliminary results show that particle-size characteristics of surface and transported sediment together with the land-surface properties can provide insights about saltation-based dust emission mechanisms and that considerable dust emission occurs in situations “sub-optimal” for sediment entrainment. Aerodynamic entrainment is hard to isolate from field measurements in an uncontrolled environment, but does occur if free dust is available. Theory suggests that the threshold friction velocity for the entrainment of dust can be as low as that for sand. A parameterization for aerodynamic entrainment will be presented and used to estimate dust devil dust emission on small and large spatial scale.