Comparison of PM_2.5 Chemical Components over East Asia Simulated by the WRF-Chem and WRF/CMAQ Models: On the Models’ Prediction Inconsistency

• Main Authors: Min-Woo Choi, Jae-Hyeong Lee, Ju-Wan Woo, Cheol-Hee Kim, Sang-Hyun Lee
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Atmosphere
• Subjects: air quality model; air quality forecast; cmaq; east asia; pm_2.5; wrf-chem
• Online Access: https://www.mdpi.com/2073-4433/10/10/618
• ISSN: 2073-4433

High levels of atmospheric concentration of PM_2.5 (particulate matters less than 2.5 μm in size) are one of the most urgent societal issues over the East Asian countries. Air quality models have been used as an essential tool to predict spatial and temporal distribution of the PM_2.5 and to support relevant policy making. This study aims to investigate the performance of high-fidelity air quality models in simulating surface PM_2.5 chemical composition over the East Asia region in terms of a prediction consistency, which is a prerequisite for accurate air quality forecasts and reliable policy decision. The WRF-Chem (Weather Research and Forecasting-Chemistry) and WRF/CMAQ (Weather Research and Forecasting/Community Multiscale Air Quality modeling system) models were selected and uniquely configured for a one-month simulation by controlling surface emissions and meteorological processes (model options) to investigate the prediction consistency focusing the analyses on the effects of meteorological and chemical processes. The results showed that the surface PM_2.5 chemical components simulated by both the models had significant inconsistencies over East Asia ranging fractional differences of 53% ± 30% despite the differences in emissions and meteorological fields were minimal. The models’ large inconsistencies in the surface PM_2.5 concentration were attributed to the significant differences in each model’s chemical responses to the meteorological variables, which were identified from the multiple linear regression analyses. Our findings suggest that the significant models’ prediction inconsistencies should be considered with a great caution in the PM_2.5 forecasts and policy support over the East Asian region.