Regional Transport Increases Ammonia Concentration in Beijing, China

摘要: To elucidate the critical factors influencing ammonia (NH3) concentration in Beijing, this study combined observational analyses, backward trajectory calculations, and meteorology–chemistry coupled simulations to investigate variations NH3 from 11 May 24 June, 2015. A significant positive correlation was found between PM2.5 concentrations Beijing. By examining relationships meteorological parameters concentration, both near-surface temperature relative humidity showed correlations with concentration. The higher were usually associated warming of upper atmosphere. Distinct wind directions noted during days top bottom 33.3% concentrations. primarily related southwesterly winds, while ones westerly northerly winds. Since there are strong emissions southern plains adjacent regional transport induced by southerly prevailing winds would increase Beijing significantly. From 23 25 May, more than one third contributed processes. Thus, joint efforts reduce whole Beijing–Tianjin–Hebei region necessary regulate