Formaldehyde (HCHO) is an important proxy for volatile organic compounds and photochemical processes that influence tropospheric ozone formation. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) mission, recently launched into geostationary orbit, provides for the first time hourly observations of HCHO and other atmospheric pollutants over North America. In support of NASA’s atmospheric monitoring goals, this study first evaluates Pandora HCHO observations against co-located NDACC FTIR measurements (Boulder, Colorado, USA; Mexico City, Mexico; and Toronto, Ontario, Canada), providing validation for the rapidly expanding Pandora network. We then assess TEMPO’s ability to capture diurnal and seasonal HCHO variability. Our results show good correlation and consistent hourly and seasonal patterns between FTIR and Pandora, while highlighting the importance of routine field calibrations and performance assessments to ensure long-term data reliability. TEMPO HCHO retrievals successfully reproduce the observed diurnal and seasonal variability; however, they exhibit a persistent underestimation of approximately 30% at the three co-located FTIR–Pandora sites, with the largest discrepancies occurring under elevated HCHO conditions. Overall, the findings demonstrate the value of TEMPO for monitoring HCHO and supporting air-quality assessments while identifying retrieval biases that require further investigation and refinement for accurate characterization of HCHO.
Correlation plots between TEMPO and FTIR HCHO Total Column measurements at three sites: Boulder, Mexico City, and Toronto. The plots are shown as density scatter plots, color-coded by the number points. Each panel includes ODR results (slope and intercept), correlation coefficient (R-value), median relative difference with standard deviation, and reference lines indicating the 1:1 and ± 20% relationships.
The paper is available at:
Ortega, I., Hannigan, J. W., Edwards, D., Stremme, W., Grutter, M., Cadena-Caicedo, A., et al. (2026). Evaluating TEMPO formaldehyde retrievals with co-located ground-based FTIR and Pandora observations. Journal of Geophysical Research: Atmospheres, 131, e2026JD046497.