EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-3479 Evaluating vertically resolved Pandora formaldehyde retrievals using airborne and ground-based in situ measurements Pandey Apoorva 1 2 Place Bryan K. 2 3 Hanisco Thomas F. https://orcid.org/0000-0001-9434-8507 2 Park Jong-Uk 2 Lind Elena S. 2 St. Clair Jason M. https://orcid.org/0000-0002-9367-5749 1 2 Delaria Erin R. 2 4 Wolfe Glenn M. https://orcid.org/0000-0001-6586-4043 2 Lopez Ronaldo https://orcid.org/0009-0001-9047-3412 5 Zimba Paul V. 5 Thornhill K. Lee 6 University of Maryland Baltimore County, Baltimore, MD, USA NASA Goddard Space Flight Center, Greenbelt, MD, USA SciGlob, Columbia, MD, USA University of Maryland, College Park, MD, USA Virginia Commonwealth University, Richmond, Virginia, USA NASA Langley Research Center, Hampton, Virginia, USA 11 08 2026 2026 1 19 Copyright: © 2026 Apoorva Pandey et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3479/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3479/egusphere-2026-3479.pdf

Pandora formaldehyde (HCHO) retrievals in the boundary layer provide continuous observations of HCHO vertical distribution, yet validation of these retrievals remains limited. This work evaluates Pandora retrievals of the vertical distribution of formaldehyde (HCHO) against aircraft in situ measurements collected at four U.S. East Coast sites during the summers of 2024 and 2025. Tropospheric columns and vertical profiles are consistent with aircraft-based observations within measurement uncertainty, with agreement that depends critically on the alignment between the Pandora viewing geometry and local horizontal concentration gradients. We further demonstrate a revised interpretation of vertical profile layer heights that improves agreement with aircraft profiles. These results support the use of Pandora HCHO observations for model evaluation and tropospheric chemistry applications.

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