Simulation of aerosol optical properties over Europe with a 3-D size-resolved aerosol model: comparisons with AERONET data

This paper aims at presenting a model-to-data comparison of the Aerosol Optical Thickness (AOT) and of a few sparse data for Single Scattering Albedo (SSA) over Europe for one year. The optical parameters are computed from a size-resolved aerosol model embedded in the POLYPHEMUS system described in Mallet et al. (2007). The methodology is first described, showing that several hypothesis can be made for several microphysical aerosol properties. The simulation is made over one year (2001); statistics and monthly time series for the simulation and AERONET data are used to evaluate the ability of the model to reproduce AOT and vertically averaged SSA fields and their variability. The relation with the uncertainties of measurements is discussed. Then a sensitivity study with respect to the mixing state of the particle, the way to compute the Aerosol Complex Refractive Index (ACRI) of a mixture and the way to take into account water uptake is carried out. The results indicate that the computation of AOT is relatively stable, while the computation of the single scattering albedo is much more uncertain.