Impact of CrIS-Derived NH3 Emission Updates on Simulated Nitrate and Ammonium Aerosols over East Asia.
Journal Article
Overview
abstract
Fine particulate matter (PM1 diameter <1 μm) strongly affects air quality and health, with sulfate, nitrate, and ammonium (SNA) as major components across East Asia. Because NH3 is a key precursor of SNA formation, accurate NH3 emission data are essential for reliable SNA simulations. This study improves NH3 emission inventories in East Asia by integrating the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and the Cross-Track Infrared Sounder (CrIS), with extensive evaluation against ground-based and aircraft observations from the Korea-United States Air Quality (KORUS-AQ) campaign. Iterative linear inversion of NH3 emissions using WRF-Chem markedly enhances simulations of nitrate and ammonium, in agreement with both the aircraft and surface measurements. The absolute biases of nitrate and ammonium were reduced from 89.7 and 50.1% to 13.6 and 0.6%, respectively, compared to the aircraft observations over Seoul. However, uncertainties in nocturnal NH3 emissions remain potential sources of nighttime biases in nitrate and ammonium. Overall, the results indicate that nitrate aerosol in most of East Asia is sensitive to NH3 emission changes. To advance our understanding of SNA formation and support effective aerosol mitigation policies, improved characterization of the diurnal cycle of NH3 emissions through ground-based monitoring and high-resolution geostationary satellite observations is urgently needed.
