Gentle Topography Increases Vertical Transport of Coarse Dust by Orders of Magnitude

The presence of coarse mineral dust in the atmosphere has been substantiated several recent measurement campaigns, which include observations particles up to and above 100 μm diameter. Yet, atmospheric models either do not larger than 20 or severely underestimate their concentrations. One possibility for underestimated concentrations is that represent enhancements particle transport due subgrid-scale topography. Here, large-eddy simulations are used combination with Lagrangian tracking assess impact gentle two-dimensional topography 50 m elevation on vertical neutrally stratified conditions. significantly increases likelihood 5 reach hundred meters altitude. Further, this by orders magnitude 60 particles. Three mechanisms observed contribute increased transport: a strong upward mean flow region uphill side topography, ejection downwind crest, enhanced dispersion wake crest. compounding effects these provide pathway emitted from surface elevations where they can be further transported into free large-scale motions such as convective plumes. While findings motivated observations, generally applicable other heavy aerosols pollen.