Simulation of long-range transport of air pollutants over Northeast Asia using a comprehensive acid deposition model

A comprehensive acid deposition modeling system (CADM) was developed to simulate the long-range transport of air pollutants and regional acidic deposition processes over Northeast Asia. The main objective of the CADM is to facilitate efficient assessment by providing explicit information on long-range transboundary processes. The implemented modeling system in CADM is composed of a numerical atmospheric model (CSU RAMS) and an Eulerian chemistry/transport/deposition model. For the model validation, CADM was used to simulate long-range transport over the Northeast Asian region during 5-12 March 2002, and the simulated concentrations were compared with both surface observations at background monitoring stations as well as aircraft measurements. Additional experiments were performed to examine the sensitivity of simulated concentrations to input fields (emission rate and meteorological fields). The simulated concentrations showed some encouraging agreements with some success for the temporal variation of surface SO ₂ concentrations in comparison with both the observation at background monitoring stations and aircraft observation. However, disagreements were significant for NO _x and O ₃ concentrations, showing large inconsistencies especially at higher levels. The magnitudes of this disagreement were found to have some dependence on both input fields of emission rate and meteorology.