Numerical simulation of Dust particle dispersion from surface to the atmosphere Xu-Hui Cai Dept. Environ. Sci., Peking University

Dust emission: -- one of the essential problem 4 The process: –surface – atmosphere – transport – deposition 4 Question: –Modeling the emission

Large Eddy Simulation (LES): -- what is LES? What can it do? 4 Principle: –resolve large eddies of turbulence explicitly –Parameterize sub-grid scale eddies 4 Capacity: –Simulate turbulence –Particle dispersion process –Dust emission (?)

Samples of LES on atmospheric turbulence 4 Thermals and motion in unstable, convective boundary layer (animate)animate 4 Neutral particle dispersion –Figure 1Figure 1 –Figure 2Figure 2

Lab. experiment LES result

Problems: 4 LES: defect for very near surface 4 Dust: heavy particle!

What we are doing: 4 Introduce in a Lagrangian stochastic (LS) particle model, capable for heavy particles 4 Couple the LS model with the LES model 4 Coupling with a land surface emission model

Summary: LES and LS model has been used for simulation of dust dispersion. Preliminary result obtained. More practical condition may take into concern. THANK YOU