Formation mechanism of NO2 distribution heterogeneity at different spatial scales

NO₂ is one of the main pollutants in the atmospheric environment, which can directly or indirectly cause harm to human health. Jiangsu province is economically developed and densely populated, and the conflict between economic development and ecological environment protection is more prominent, which causes its mean annual NO₂ concentration to be higher than other neighboring provinces. The study takes the formation mechanism of NO₂ concentration distribution heterogeneity at different spatial scales as the research object. By using OMI satellite remote sensing data and NO₂ concentration ground monitoring data in Jiangsu Province from 2015 to 2020, the paper studies NO₂ concentration distribution heterogeneity at macroscopic and microscopic scales, respectively, to analyze the formation mechanism. The results show that: (1) The spatial distribution characteristics of NO₂ concentration obtained based on the analysis of two data sources have good consistency, with the overall performance of high NO₂ concentration in the south of Jiangsu where the concentration of NO₂ column reached 16.3 × 10¹⁵ molec/cm ² and the monitoring concentration reached $46.3\mu g$/m³, while the concentration of NO₂ in central Jiangsu is relatively low, with average concentrations of 6 × 10¹⁵ molec/cm ² and $26\mu g$/m³. (2) Under the macroscopic spatial scale, the average NO₂ column concentration in the south of Jiangsu is 9 × 10¹⁵ molec/cm ² higher and the monitoring concentration is $15\mu g$/m³ than that in the north of Jiangsu; natural factors such as temperature are the important influencing factors for the heterogeneity of NO₂ concentration distribution under this scale. (3) At the microscopic spatial scale, NO₂ concentration is 5–10% higher in industrial concentrations in southern Jiangsu, some heating cities in northern Jiangsu, and industrial parks in northern Jiangsu. In addition, NO₂ concentration decreases gradually with distance from this area; anthropogenic factors such as population density, GDP, and car ownership are important factors to influence the heterogeneity of NO₂ concentration distribution at this scale. Based on the above findings, the paper proposes to adjust the industrial structure, limit the number of high energy-consuming and high-emission enterprises, and develop seasonal emission reduction measures.