Synthesizing evidence for the external cycling of NOx in high- to low-NOx atmospheres

Chunxiang Ye; Xianliang Zhou; Yingjie Zhang; Youfeng Wang; Jianshu Wang; Chong Zhang; Robert Woodward-Massey; Christopher Cantrell; Roy L Mauldin 3rd; Teresa Campos; Rebecca S Hornbrook; John Ortega; Eric C Apel; Julie Haggerty; Samuel Hall; Kirk Ullmann; Andrew Weinheimer; Jochen Stutz; Thomas Karl; James N Smith; Alex Guenther; Shaojie Song

doi:10.1038/s41467-023-43866-z

Synthesizing evidence for the external cycling of NO_x in high- to low-NO_x atmospheres

Nat Commun. 2023 Dec 2;14(1):7995. doi: 10.1038/s41467-023-43866-z.

Authors

Chunxiang Ye¹, Xianliang Zhou^{2

3}, Yingjie Zhang^{4

5}, Youfeng Wang⁴, Jianshu Wang⁴, Chong Zhang⁴, Robert Woodward-Massey^{4

6}, Christopher Cantrell⁷, Roy L Mauldin 3rd^{8

9

10}, Teresa Campos¹¹, Rebecca S Hornbrook¹¹, John Ortega¹¹, Eric C Apel¹¹, Julie Haggerty¹¹, Samuel Hall¹¹, Kirk Ullmann¹¹, Andrew Weinheimer¹¹, Jochen Stutz¹², Thomas Karl¹³, James N Smith¹⁴, Alex Guenther¹⁴, Shaojie Song¹⁵

Affiliations

¹ State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKL-ESPC), College of Environmental Sciences and Engineering, Peking University, Beijing, China. c.ye@pku.edu.cn.
² Wadsworth Center, New York State Department of Health, Albany, NY, USA.
³ Department of Environmental Health Sciences, State University of New York, Albany, NY, USA.
⁴ State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKL-ESPC), College of Environmental Sciences and Engineering, Peking University, Beijing, China.
⁵ School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China.
⁶ Department of Chemistry, University of Leeds, Leeds, UK.
⁷ Université Paris-est Créteil, LISA (Laboratoire Interuniversitaire des Systèmes Atmosphériques), Paris, France.
⁸ Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA.
⁹ Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA.
¹⁰ Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO, USA.
¹¹ National Center for Atmospheric Research, Boulder, CO, USA.
¹² Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA.
¹³ Institute for Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria.
¹⁴ Earth System Science, University of California, Irvine, CA, USA.
¹⁵ State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin, China.

Abstract

External cycling regenerating nitrogen oxides (NO_x ≡ NO + NO₂) from their oxidative reservoir, NO_z, is proposed to reshape the temporal-spatial distribution of NO_x and consequently hydroxyl radical (OH), the most important oxidant in the atmosphere. Here we verify the in situ external cycling of NO_x in various environments with nitrous acid (HONO) as an intermediate based on synthesized field evidence collected onboard aircraft platform at daytime. External cycling helps to reconcile stubborn underestimation on observed ratios of HONO/NO₂ and NO₂/NO_z by current chemical model schemes and rationalize atypical diurnal concentration profiles of HONO and NO₂ lacking noontime valleys specially observed in low-NO_x atmospheres. Perturbation on the budget of HONO and NO_x by external cycling is also found to increase as NO_x concentration decreases. Consequently, model underestimation of OH observations by up to 41% in low NO_x atmospheres is attributed to the omission of external cycling in models.

Abstract

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