Study of Surface Layer Characteristics in the Presence of Suspended Snow Particles Using Observational Data and Large Eddy Simulation

A snowdrift is a two-phase flow consisting of air and suspended particles. In the presence of snow particles in the air, additional stability appears in the surface layer due to the density gradient. The density gradient reduces turbulence and affects the properties of the surface layer. Therefore, to describe the properties of the flow with included snow particles, additional clarifications are required. A description of the surface layer parameterization with the presence of suspended snow particles is presented in this paper. The formulation of the effect of snow particles consists of the reformulation of the Obukhov turbulent length scale. The novel surface layer parameterization allows one to take into account the effect of snow particles on turbulent flow and may improve the estimates of friction velocity and boundary-layer height.The parameterization was successfully tested on the observational data. A description of snow particle influence has been included in the large eddy simulation (LES) model. The numerical experiments confirmed an increase in the stability of the surface layer. The mechanism of influence of suspended particles on the surface layer is analogous to a thermal stabilization of the turbulent flow, in which negative buoyancy acts to reduce the turbulent kinetic energy (TKE).