Wind-tunnel Experiment on Dust Atmosphere-surface Exchange: Emission and Dry Deposition

A series of wind tunnel experiments are carried out to study dust atmosphere-surface exchange, including emission and dry deposition. The gradient method is employed to measure the dust emission rate. And the PDA (Particle Dynamics Analysis) technique is applied for the measurement of dust deposition velocity. The experimental results indicate that saltation bombardment is a predominantly reason for dust emission from sandy loam surface. And the emission rate scales with u*4 to u*5. Except for horizontal saltation flux, the sandblasting efficiency intimately affects dust emission rate and increases with the increasing friction velocity by following an exponential law. The dust deposition velocity increases with particle size, for particles bigger than0.75 μm. Besides wind friction velocity, the roughness elements on surface can significantly enhance dust dry deposition, especially for dust smaller than 4 μm.