Abstract
<jats:p>Abstract. 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.</jats:p>