Field measurements and size-resolved model simulations of turbulent particle transport to a forest canopy

Abstract

Direct measurements of turbulent particle number fluxes above a Norway spruce forest are compared with a size-resolved particle deposition model in combination with particle size distribution measurements. In most cases, the model output is in reasonable agreement with the eddy covariance measurements. The combination of deposition model and size distribution measurements allows the evaluation of size-resolved particle number and mass fluxes. While turbulent particle number fluxes are dominated by ultrafine particles below 50 nm diameter, submicron particle mass fluxes are established mainly in the accumulation mode. The effective deposition diameter Ded is introduced as a new parameter to describe the effect of the size distribution of a polydisperse particle population on the integral particle transfer velocity.