Behavior of air particles associated with atmospheric recirculation over complex coastal area

Abstract

Several numerical experiments were carried out over Gwangyang Bay area, which is located southwestern part of the Korean Peninsula, to clarify the characteristics of the recirculation potential and the impact of the spatial size of the model domain on air pollutant dispersion. The numerical models used in this study were Weather and Research Forecasting (WRF) model to assess the atmospheric circulation and FLEXPART to estimate the level of pollutant dispersion. Regardless of the synoptic conditions, the variation in the recirculation potential based on the transported distance of air pollutants agreed well with the change in ozone concentration. Weak synoptic wind and strong regional flow results in the highest recirculation potential in both inland and coastal areas. The concentration in limited areas is strongly associated with the pollutants recirculated by regional circulation. The persistence of synoptic wind often prevents particle recirculation but intensified regional circulation around coastal area is favorable for increasing the returning particles. Therefore, the determined domain size should be large enough to include the trace of recirculated pollutants when weak synoptic wind occurs.