Size-resolved aerosol pH over Europe during summer

Abstract. The dependence of aerosol acidity on particle size, location, and altitude over Europe during a summertime period is investigated using the hybrid version dynamics in chemical transport model PMCAMx. pH changes more with size northern southern owing to enhanced presence non-volatile cations (Na, Ca, K, Mg) larger particles. Differences up 1–4 units are predicted between sub- supermicron particles, while average PM1?2.5 can be as much 1 unit higher than that PM1. Most water continental associated PM1, coarse particles dominate content marine coastal areas due relatively levels hygroscopic sea salt. Particles all sizes become increasingly acidic (0.5–2.5 decrease 2.5 km) primarily because liquid (driven by humidity changes) height. Inorganic nitrate strongly affected highest for PM1?5 range locations where exceeds 3. Dust tends increase concentrations This effect dust quite sensitive its calcium content. size-dependent differences carry important implications pH-sensitive processes aerosol.