An investigation on NH3 emissions and particulate NH4+–NO3− formation in East Asia

In this study, the accuracy of NH3 emissions in East Asia is evaluated by a comparison of measured and predicted NH4NO3 concentrations. For the prediction of particulate NH4NO3 concentrations, this study uses the USEPA Models-3/Community Multi-scale Air Quality (Models-3/CMAQ) model. The measurement data are collected from 4 ground-based stations (Beijing, Shanghai, Qingdao, and Kangwha) and ACE-ASIA C130 Flights #6, #7, and #10. The four ground-based stations and air flight tracks are located in and around the Yellow Sea in East Asia. According to the results, the predicted fine-mode NH4+concentrations are 1.2–3.8 times overestimated compared to those measured on the mass basis, and fine-mode NO3− concentrations are 1.9–7.6 times overestimated on the mass basis. It is also revealed in this study that aberrantly high predicted fine-mode NO3− concentrations in East Asia can be attributed to the overestimated NH3 emissions. The predicted gas-phase NH3 concentrations and estimated NH3 emissions are likely to be 1.2–3.8 times overestimated in East Asia on the mass basis. Therefore, it is recommended that approximately 20–75% reduced NH3 emission fields should be used in future modeling studies for East Asia.