Effect of small-scale turbulent fluctuations on rates of particle formation

The effect of small-scale turbulent fluctuations on new particle formation in the atmosphere was examined. Large Eddy Simulation data were used for typical conditions inside the Planetary Boundary Layer (PBL) in conjunction with a numerical model to calculate the binary nucleation rate of the sulfuric acid-water system. Six different averaging procedures were chosen to elucidate the spatial variability of the binary nucleation rate. We found that the usual small-scale fluctuations in the PBL exert locally a considerable effect on the rate of new particle formation. This effect, however, becomes much less important in terms of the average nucleation rate. For artificially enhanced turbulent fluctuations the effect on the average nucleation rate becomes more pronounced (at least a factor 2) though still not extreme considering the usual uncertainties in nucleation-rate calculations and measurements.