Assessment of the atmospheric mixing layer height and its effects on pollutant dispersion

The atmospheric mixing layer height (MLH) is an important parameter of the planetary boundary layer (PBL) because it affects the transportation and dispersion processes of pollutants emitted from different sources. This study investigated the relationship between the surface temperature inversion, elevated temperature inversion, and MLH within the PBL of the Kuwait by collecting and analyzing measurements of the temperature and the air quality of upper air during 2013. The upper air temperature and the MLH were derived using a microwave temperature profiler. Hourly concentrations of SO₂, O₃, particulate matter (PM₁₀), NO₂, CO, NO _x , and non-methane hydrocarbons (NMHCs) in ambient air were measured by air quality monitoring stations. The collected data were used to estimate the hourly MLH for the transportation and dispersion of critical pollutants. The results showed that concentrations of SO₂ and PM₁₀ have direct correlation with MLH during the day, whereas they have the reverse relationship at night. Conversely, concentrations of CO, NMHCs, and NO _x showed negative correlation with MLH during both day and night, whereas concentrations of O₃ showed direct correlation with MLH during both day and night. In addition, the relationship between the PBL and concentrations of critical pollutants in residential areas was clarified. These findings indicate the influence of the MLH on SO₂ and PM₁₀ is much greater during the day than at night. The findings of the present study could help improve our understanding of the effects of MLH on air quality.