Multi-scale simulation of vertical dust transport considering turbulent motions

Abstract

Analysis of observational data shows that the different scale dust transportation events have different contributions to dust transportation. The large-scale dust concentration fluctuations (dimensionless based on dust concentration) have a good linear relationship with large-scale shear wind speed (dimensionless based on frictional wind speed), and small-scale fluctuations have the similar results. Therefore, this multi-scale characteristic needs to be considered in the dust transport prediction. Guided by this idea, a multi-scale dust transport model based on the turbulent motions at different scales is proposed. The prediction results are in good agreement with the observation results. The analysis of the prediction results reveals the spatial variation of the dust concentration, the large-scale and small-scale vertical dust flux along the height. At the same time, our results show that under the action of large-scale turbulent motions, a channel for dust upward transportation will be formed, but not all large-scale turbulence events can transport dust to the upper part of the atmospheric surface layer. The small-scale turbulent motions does not affect the location of the dust transport channel, however mainly affects the size of the dust concentration, that is, ignoring the effect of small-scale turbulent motions will cause an overestimation of the dust concentration.