Correlations between TEMPO Tropospheric NO2 Observations and EPA AQS Ground-level NO2 Measurements over Metro New York

This study compares TEMPO tropospheric NO2 to the EPA Air Quality System (AQS) ground-level NO2 measurements in the New York City metropolitan area from August 2023 to February 2024. Tropospheric NO2 columns from satellite measurements are considered highly correlated with their corresponding ground-level NO2 measurements. This is because the overpass time of LEO satellites is often in the early afternoon, when the planetary boundary layer reaches daily maximum and is well-mixed. However, this high correlation between satellite-based tropospheric NO2 and ground-level NO2 concentrations may not exist at other times of the day, such as early morning and late afternoon rush hours. Ground-level NO2 daily maximums occur during rush hours and can be critical information for local stakeholders’ decision-making process. TEMPO is the first geostationary instrument to observe air pollutants over North America during daytime hours. This research investigates those NO2 correlations during daytime in a highly urbanized area with a high concentration of NO2 issues utilizing this new instrument. This study improves the use of TEMPO NO2 data on local air pollution management.