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 46.3μg/m3, while the concentration of NO2 in central Jiangsu is relatively low, with average concentrations of 6 × 1015 molec/cm 2 and 26μg/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 15μg/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.