Temporal Variation of Temperature Inversions and their Effect on Fine Particulate Matter (PM2.5) Concentrations in a Vietnamese Metropolis

This study aims to investigate the temporal variation of temperature inversions, including inversion frequency and inversion strength, in Ho Chi Minh City (HCM), a metropolis of Vietnam. The effect of the temperature inversions on PM2.5 concentrations in the dry and rainy seasons of HCM City was also identified. The results revealed that the surface inversions, which are temperature inversions below 300 m, were more frequent at 12Z (7 PM local time) in the rainy season. In addition, the stronger inversions were found in the dry season, when the higher PM2.5 concentrations were also observed, suggesting an influence of the temperature inversions on an increase in PM2.5 concentrations. This suggestion was also supported by the significantly positive correlation between PM2.5 concentrations and inversion frequency in the dry season. However, the temperature inversions were believed to have a minor effect on the PM2.5 concentrations in the rainy season since no significant correlation between the PM2.5 concentrations and inversion frequency or strength was found for this season. The findings of this study contribute to understanding of the temperature inversions and their effect on PM2.5 concentrations in a metropolis of Vietnam, a developing country in Southeast Asia. Based on these results, solutions for reducing the PM2.5 pollution in the study area can be obtained.