Below-cloud scavenging of fine particles by convective precipitation in Milan’s metropolitan area

摘要

High suspended aerosol concentration in low atmosphere is a key issue in urban sites like the metropolitan area of Milan. The exposure to high concentration of fine particles causes short-term health effects and increases the possibility of contracting serious chronic respiratory and cardio circulatory diseases. Furthermore, the flat conformation of the area under exam and the scarcity of winds, implying very low dry deposition, help to make the issue even more vital. In this context, wet deposition becomes fundamental, being almost the only mechanism to clean the air. The main goal of this study is to determine how efficient is the convective precipitation, which is characterized by high rainfall intensities, at scavenging aerosol particles at this singular urban site.