New Publication C-shaped nitrous acid profiles in the troposphere
Benjamin Weyland and co-workers report on a C-shaped concentration profile of nitrous acid (HONO) in the troposphere. For various campaign data taken from onboard the HALO research aircraft, their DOAS measurements indicate abundances of up to 150 ppt in the planetary boundary layer, a few 10 ppt up to 100 ppt in the upper troposphere and smaller concentrations in-between. These abundances exceed model predictions by an order of magnitude and suggest photochemical mechanisms at play that have so far been neglected or are unknown and unquantified. Several hypotheses are explored to explain the findings.
Weyland, B., Rosanka, S., Taraborrelli, D., Bohn, B., Zahn, A., Obersteiner, F., Förster, E., Mertens, M., Jöckel, P., Ziereis, H., Kaiser, K., Fischer, H., Crowley, J. N., Wang, N., Edtbauer, A., Williams, J., Andrés Hernández, M. D., Burrows, J. P., Kluge, F., Rotermund, M. K., Butz, A., and Pfeilsticker, K.: Airborne remote sensing of nitrous acid in the troposphere: potential sources of excess HONO, Atmos. Chem. Phys., 26, 6825–6856, 2026.