A nitrate photolysis source of tropospheric HONO is incompatible with current understanding of atmospheric chemistry

Rowlinson, Matthew J.; Carpenter, Lucy J.; Evans, Mat J.; Lee, James D.; Andersen, Simone T.; Sherwen, Tomas; Callaghan, Anna B.; Sommariva, Roberto; Bloss, William; Hou, Siqi; Crilley, Leigh R.; Pfeilsticker, Klaus; Weyland, Benjamin; Ryerson, Thomas B.; Veres, Patrick R.; Campuzano-Jost, Pedro; Guo, Hongyu; Nault, Benjamin A.; Jimenez, Jose L.; Fomba, Khanneh Wadinga

doi:10.5194/acp-25-16945-2025

Articles | Volume 25, issue 22

https://doi.org/10.5194/acp-25-16945-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-25-16945-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 22

Research article

|

27 Nov 2025

Research article |

| 27 Nov 2025

A nitrate photolysis source of tropospheric HONO is incompatible with current understanding of atmospheric chemistry

Matthew J. Rowlinson, Lucy J. Carpenter, Mat J. Evans, James D. Lee, Simone T. Andersen, Tomas Sherwen, Anna B. Callaghan, Roberto Sommariva, William Bloss, Siqi Hou, Leigh R. Crilley, Klaus Pfeilsticker, Benjamin Weyland, Thomas B. Ryerson, Patrick R. Veres, Pedro Campuzano-Jost, Hongyu Guo, Benjamin A. Nault, Jose L. Jimenez, and Khanneh Wadinga Fomba

Supplement

https://doi.org/10.5194/acp-25-16945-2025-supplement

Data sets

MASTER: FIREX-AQ Airborne Campaign, Western-Central USA, Summer 2019 (Version 1.2) S. J. Hook et al. https://doi.org/10.3334/ORNLDAAC/1941

ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols (Version 1.5) S. C. Wofsy et al. https://doi.org/10.3334/ORNLDAAC/1581

Model code and software

Code associated with the publication Mat Evans and Matthew Rowlinson https://doi.org/10.5281/zenodo.17115643

geoschem/GCClassic: GCClassic 14.4.2 The International GEOS-Chem User Community https://doi.org/10.5281/zenodo.12809895

Code used for "A nitrate photolysis source of tropospheric HONO is incompatible with current understanding of atmospheric chemistry" Rowlinson et al. M. Rowlinson https://doi.org/10.5281/zenodo.17483547

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Short summary

HONO is key to tropospheric chemistry. Observations show high HONO concentrations in remote air, possibly explained by nitrate aerosol photolysis. We use observations to parameterize nitrate photolysis, evaluating simulated HONO against observations from multiple sources. We show improved agreement with observed HONO, but overestimates in NO_x and O₃, beyond observational constraints. This implies uncertainties in the NO_x budget and our understanding of atmospheric chemistry.