Aerosol removal due to precipitation and wind forcings in Milan urban area

摘要

Highlights?Below-cloud scavenging coefficients show mean values between 2×10?5and 5×10?5s?1.?Removal efficiency induced by wind and precipitation are compared.?Wind removal increases, while precipitation removal decreases with particle size.?Investigation of precipitation-aerosol dynamics in Milan.AbstractAir pollution represents a critical issue in Milan urban area (Northern Italy). Here, the levels of fine particles increase, overcoming the legal limits, mostly in wintertime, due to favourable calm weather conditions and large heating and vehicular traffic emissions. The main goal of this work is to quantify the aerosol removal effect due to precipitation at the ground. At first, the scavenging coefficients have been calculated for aerosol particles with diameter between 0.25 and 3μm. The average values of this coefficient vary