Applications of WRF/CALPUFF modeling system and multi-monitoring methods to investigate the effect of seasonal variations on odor dispersion: a case study of Changwon City,South Korea

Changwon is an industrial city located in the southeastern region of South Korea. Surrounded by coastal and mountainous areas with contiguous industrial and residential areas, the city of Changwon has experienced a high number of malodor complaints in recent years. This study was carried out to investigate the effect of seasonal variations on odor dispersion from industrial to community areas, which were considerably higher from the late spring through fall according to complaint statistics. Investigation methods comprise the applications of electronic odor detector, questionnaire, olfactory system, weather observation data, and weather research and forecasting/CALPUFF modeling system. Results from all methods were consistent in showing that the change of seasons affected the direction of odor diffusion. From summer to early fall, the pollutions emitted from the industrial zone had the highest impact on the residential zone, covering the three most common areas of complaints for unpleasant odors. The reasons are that during the summer period, the reduction of a planetary boundary layer and the prevalence of a consistent sea breeze resulted in the presence of south–southwesterly ocean winds which swept through the factories to a residential area. In contrast, synoptic winds which prevailed during other seasons restrained sea breeze circulation, leading to diverse wind directions. During the fall season, the higher number of complaints could be attributed to a lower wind speed, which caused the poor spread of pollutants from the area with the topography of the basin.