Laboratory intercomparison of the formaldehyde absorption cross sections in the infrared (1660–1820 cm⁻¹) and ultraviolet (300–360 nm) spectral regions

Formaldehyde plays a key role in atmospheric photochemistry and is particularly important for the production of HOx species. For measuring atmospheric formaldehyde concentrations, both midinfrared and ultraviolet (UV) absorption techniques are used by ground‐, air‐ or satellite‐based instruments. In order to obtain accurate formaldehyde concentrations, the knowledge of the absorption cross sections is of utmost importance. In this study, we report the first laboratory intercomparison of the absorption coefficients of formaldehyde using simultaneous measurements in both spectral regions. The intercomparison shows good agreement between selected accurate UV spectra published previously and different infrared data. On the contrary, a rather large disagreement (about 20%) is observed when using other UV data sets, such as those recommended currently by the HITRAN database.