Background, urban, and industrial NO2 estimated from TEMPO satellite observations

The hourly tropospheric NO2 vertical column density (VCD) values measured by TEMPO were used to study the NO2 diurnal andseasonal variability in 34 urban areas over North America and the Caribbean during the period from August 2023 to October 2024. A recently developed algorithm (Fioletov et al., 2024) isolated three components in tropospheric NO2 data: background NO2, NO2 from urban emissions, and from industrial point sources, and then each of these components was analyzed separately. The method is based on fitting satellite data by a statistical model with empirical plume dispersion functions driven by a meteorological reanalysis. Population density and surface elevation data as well as coordinates of major industrial sources were used in the analysis. The background component demonstrated a clear diurnal cycle with a maximum in the early morning and the minimum in the late afternoon. The urban and industrial components, expressed as total NO2 mass in urban and industrial plumes, did not show any obvious diurnal cycle in most areas. Only the Los Angeles and Mexico City urban components demonstrated a clear cycle with a maximum in the late morning and a minimum in the late afternoon. Differences between workday and weekend NO2 levels were also studied. Urban plume NO2 values on Sundays were typically 30%–60% less than workday plume values throughout the day.  The exception was Havana, where the difference between working day and Sunday values ​​was only 15%. Fioletov, V., McLinden, C. A., Griffin, D., Zhao, X., and Eskes, H.: Global seasonal urban, industrial, and background NO2 estimated from TROPOMI satellite observations, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-1991, 2024.