Dynamic characteristics of snowfall particles in atmospheric turbulent boundary layer and its effect on dust wet deposition

Abstract. Wet deposition by snowfall refers to the scavenging of atmospheric dust by snow particles. Existing models only consider vertical scavenging in quiescent atmosphere, neglecting the complex vertical and horizontal motion of snowfall particles induced by turbulence in the actual atmosphere boundary layer, affecting the accurate estimation of wet deposition flux. However, precise quantitative analysis of dust collection mechanism during snow particle setting remains lacking under turbulence. Therefore, we employ the Euler-Lagrange numerical method to simulate and analyze snow particles dynamic characteristics and dust collection in turbulent boundary layers. It is shown that increasing friction velocity (u*) alters the dominant factors controlling the relative motion between snow particles and air. The transition occurs at a critical dimensionless parameter αd = Vt/κu* = 0.2 (Vt is the terminal settling velocity of snow particles, and κ = 0.4 is the von Kármán constant). When αd>0.2, the vertical relative motion dominates, and its dominance strengthens with increasing αd; when αd