A Comparative Analysis of TEMPO NO ₂ Remote Sensing With Surface‐Level Monitoring Through Diurnal and Seasonal Trends, Meteorology, and Monitor Characteristics

Abstract The NASA Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument—launched in August 2023—measures diurnal patterns of column NO 2 at unprecedented spatial resolution. Given its nascent status, it is unknown how TEMPO V03 column NO 2 compares to surface‐level monitoring across long‐term timescales. In this study, we explore how temporally averaged hourly TEMPO column NO 2 observations compare to surface‐level concentrations from monitors in the US EPA Air Quality System (AQS). Monthly averaged hourly TEMPO vertical column densities (VCDs) correlate to surface‐level NO 2 moderately ( R 2 = 0.42); however, there is notably stronger correlation for monitors that are not defined as “near road” across hourly annual‐average equivalent timescales ( R 2 = 0.61). During the TROPOMI overpass (approximately 13:30 LT), annual‐average TEMPO slant column densities (SCDs) at “not near road” sites are better correlated with surface‐level NO 2 ( R 2 = 0.72) than tropospheric VCDs from TROPOMI ( R 2 = 0.65) and TEMPO ( R 2 = 0.66) due to added uncertainty with a priori inputs in the AMF. In the future, a more accurate AMF could improve TEMPO VCDs correlation to the level of the TEMPO SCDs. TEMPO column NO 2 are most poorly correlated in the early morning at 6:00 ( R 2 = 0.23) and 7:00 ( R 2 = 0.35) LT when TEMPO is less sensitive to near‐surface pollution due to a longer sunlight path through the atmosphere and the subsequent increased sensitivity to retrieval assumptions. Ultimately, this analysis identifies conditions and characteristics that affect the correlation between TEMPO and ground‐level monitoring that has implications for applying TEMPO remote sensing data to derive or interpret surface‐level NO 2 .