Nocturnal fine particulate nitrate formation by N2O5 heterogeneous chemistry in Seoul Metropolitan Area, Korea

摘要: Abstract This study investigated the potential of fine nitrate (NO3− in PM2.5) formation Seoul Metropolitan Area (SMA) by nighttime dinitrogen pentoxide (N2O5) heterogeneous chemistry during March 16–18, 2016, relatively dry and stagnant early spring days, intervening N2O5 uptake coefficients (reactive probability, γN2O5) modeling with WRF-CMAQ. Simulations a base case two sensitivity tests default (Davis et al., 2008), zero decupled (tenfold) γN2O5 showed that impacts on NO3− PM2.5 are sensitive to relative humidity (RH) sulfate-nitrate-ammonium (SNA) conditions. The simulation generally underestimated levels comparison observations. Even γN2O5, modeled concentrations small increases under conditions RH is low range 20 40% SNA severely (e.g., lower one third) simulation. Comparisons SMA between simulations differently specified indicated has (1) form additional nitric acid (HNO3), (2) further react ammonia (NH3) emitted from various sources including agricultural outside urban-core areas, (3) contribute SMA. Additional observational studies needed improve our understanding better forecast pollution over or other urban areas abundant nitrogen oxides emissions such as surrounding areas.