Unveiling the impact of temperature inversions on air quality: a comprehensive analysis of polluted and severe polluted days in Istanbul

The main reason that deteriorates air quality in mega cities is the increase in concentrations of air pollutant parameters. Meteorological parameters and atmospheric conditions play an important role in the increase of pollutant concentrations. This study provides insights into temperature inversions (TIs) during polluted days (PDs) and severe polluted days (SPDs) in Istanbul. Key findings include higher inversion frequencies during SPDs, particularly at 0000 UTC, along with a positive relationship between inversion frequencies and pollutant concentrations, notably with a 99% occurrence of inversions at 0000 UTC along SPDs. Analysis of inversion subgroups reveals surface-based inversions (SBIs) dominating at 0000 UTC, while elevated (EIs) and lower-troposphere inversions (LTIs) prevail at 1200 UTC. Winter months exhibit increased frequency and intensity of SBIs, aligning with expectations of subsidence motion under high-pressure systems. Inversion strengths and depths are higher during SPDs, with the highest strengths observed in winter at 0000 UTC and the deepest inversions occurring in winter for SPDs. Generally, the highest inversion strengths and shallowest inversion depths were observed in SBIs. EIs had the lowest frequency during the winter months, while LTIs occurred more often in the spring months. These findings underscore the importance of understanding TI patterns for effective air quality management in Istanbul.