Spatiotemporal patterns of nitrogen dioxide (NO₂) in an arid industrial region: integrating satellite and ground observations (2018–2023)

Air pollution in rapidly urbanizing arid regions is an escalating environmental challenge, yet few studies have systematically investigated how industrial growth and seasonal energy consumption affect nitrogen dioxide (NO₂) dynamics in such climates. Although numerous localized investigations exist, the lack of regionally transferable frameworks has limited comparative assessments across arid developing regions. This study integrates Sentinel-5P satellite observations with ground-based air-quality monitoring and AERMOD dispersion modeling to analyze spatiotemporal NO₂ trends in Isfahan, central Iran, considered a representative case of semi-arid industrial cities in developing regions. The results reveal a statistically significant increase in NO₂ column density between 2018 and 2023 (p < 0.01), with pronounced seasonal variability—peaking in winter and declining in summer—largely driven by fossil-fuel consumption for heating and industrial activities and constrained vertical mixing due to atmospheric temperature inversions. Average NO₂ concentrations increased from approximately 194 μmol/m² in spring 2018 to 237 μmol/m² in spring 2023, and from 329 μmol/m² in winter 2018 to 356 μmol/m² in winter 2023, highlighting a consistent upward trend across seasons that mirrors patterns observed in other arid industrial regions. Dispersion modeling indicates that fuel–oil combustion at the Shahid-Montazeri Power Plant produces approximately 2.5 times higher NOₓ emissions than natural-gas operation. By combining remote sensing and dispersion modeling, this study provides a transferable framework for high-resolution air-quality assessment in regions with limited monitoring infrastructure. These insights not only advance understanding of NO₂ dynamics in arid urban environments but also inform emission-control strategies applicable to cities facing similar climatic and industrial conditions worldwide.