Large Eddy Simulations of the Dusty Martian Boundary Layer and Dust Devils with MarsWRF

Large eddy simulations (LES) of meteorological process and dust transport in the Martian convective boundary layer (CBL) are performed employing a Mars version of the Weather Research and Forecasting model (WRF), adapted to use periodic boundary conditions. A wind stress dust lifting scheme is used to determine dust lifting, and the lifted dust is entrained into the updraught. Surface albedo, thermal inertia and solar forcing are set uniform across the domain, using values obtained from the MarsWRF General Circulation Model (GCM) at the same locations. We examined the effects of dust on the CBL process. The dusty atmosphere will shade the sunlight and weaken the convection process. However, the inhomogeneous dust distribution will enhance the thermal contrast both at the surface and in the atmosphere and induce more energy into the CBL by increasing the buoyant production. If the lifting rate is large enough, the extra energy due to the inhomogeneous effect may exceeds the decreased energy due to the shading effect and the overall effect results in the higher CBL height at the end of the afternoon. The dynamical process of dust within the dust devils is also investigated. The dust is mostly lifted in the ring of the maximum winds. The vertical structures of dust in the simulated and observational dust devils are compared. Then we present some insights on several issues like how much detrainment happens from the dust devil, how deep the dust is injected compared to the CBL top, and how rapidly the dust is lifted through the dust devils, etc.