Numerical Sensitivity Study on a Mega Sand Dust Storm in Korea Using WRF-Chem

This study evaluates the performance of the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) in forecasting a mega Asian Dust Storm (ADS) event that occurred over Korea on March 28–29, 2021. Since the introduction of the ADS crisis warning system in Korea in 2015, a nationwide caution stage was announced for the first time in six years on March 29, 2021. We specifically evaluated a combination of parameterization schemes: five for dust emission and four for land surface schemes, which are crucial for the accurate numerical forecasting of dust storms. Using in-situ and remote sensing data, we comprehensively evaluated meteorological and air quality variables, including 2 m temperature, 2 m relative humidity, 10 m wind speed, PM10, and aerosol optical depth (AOD) over Korea. Our results indicate that the prediction performance of surface meteorological variables was influenced more by the land surface scheme than by the dust emission scheme, with scheme combinations based on Noah land surface model with Multiple Parameterization options (Noah-MP) generally showing good performance. In contrast, in predicting air quality variables, including Particulate Matter 10 (PM10) and AOD, there was a very large difference in performance depending on the scheme combinations due to the influence of the dust emission scheme, which is directly related to the generation and amount of dust. Based on the evaluation results of various combinations of dust emission and land surface schemes in this study, we can suggest appropriate combination schemes for the WRF-Chem model in cases of mega ADSs affecting Korea.