Aerosol Science 35 (2004) 545–559 www.elsevier.com/locate/jaerosci Eect of small-scale turbulent uctuations on rates of particle formation C. Housiadas a ; * , Y. Drossinos b , M. Lazaridis c a “Demokritos” National Centre for Scientic Research, P.O. Box 60228, 15310 Agia Paraskevi, Athens, Greece b Institute for Environment and Sustainability, Joint Research Centre, European Commission, I-21020 Ispra (Va), Italy c Department of Environmental Engineering, Technical University of Crete, 73100 Chania, Greece Received 13 June 2003; received in revised form 21 October 2003; accepted 27 October 2003 Abstract The eect of small-scale turbulent uctuations 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 dierent averaging procedures were chosen to elucidate the spatial variability of the binary nucleation rate. We found that the usual small-scale uctuations in the PBL exert locally a considerable eect on the rate of new particle formation. This eect, however, becomes much less important in terms of the average nucleation rate. For articially enhanced turbulent uctuations the eect 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. ? 2003 Elsevier Ltd. All rights reserved. Keywords: Large Eddy Simulation; Binary nucleation; Turbulent mixing 1. Introduction Long-range transport of photochemical gaseous air pollutants and particulate matter (PM) has been studied extensively over the last decade under the framework of several national and international programmes (e.g. Andreae & Crutzen, 1997). However, information is still limited on consistent measurements and subgrid-scale modelling studies to reveal the atmospheric composition and spa- tial variability of ozone and PM and its contribution to atmospheric air quality (see, for example, ∗ Corresponding author. Tel.: +30-210-650-3702; fax: +30-210-653-3431. E-mail address: christos@ipta.demokritos.gr (C. Housiadas). 0021-8502/$ - see front matter ? 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaerosci.2003.10.012