Observationally Constrained NO x ‐Catalyzed Ozone Production in the Upper Troposphere During the Asian Summer Monsoon
Year: 2025
Type: article
Abstract: Intense and frequent convection occurring during the Asian Summer Monsoon (ASM) rapidly transports surface emissions to the upper troposphere (UT). Depending on their chemical reactivities, pollutants transported to the UT via this mechanism may either undergo chemistry in the UT region or be transported into the lower stratosphere. The Asian Summer Monsoon Chemical and CLimate Impact Project (ACCLIP) used high‐altitude research aircraft to characterize chemistry in the tropopause region within the ASM anticyclone and outflows of monsoon convection during summer 2022. Here, we use measurements of trace gases from ACCLIP and results from a 0‐D model constrained by airborne observations to calculate net ozone production rates in airmasses influenced by recent convection and in the summer monsoon background upper troposphere/lower stratospheric air. We find that ozone production inside the polluted air downstream of recent convection is up to one order of magnitude higher than that in the cleaner background upper troposphere. The ozone production is driven by NO + HO 2 produced from CO and OVOC oxidation, rather than from organic peroxy radicals produced from volatile organic compounds inside the highly polluted airmasses. Consistent with previous modeling work, we find efficient HO x (OH + HO 2 ) cycling is dominated by reactions with CO. Ozone production in this region is primarily NO x ‐limited and increases with higher NO x such as during convective events with lightning NO x production. Further, we find that the dominant impact of enhanced NO x here is through acceleration of HO x cycling, and thus an increase in ozone production.
DOI: 10.1029/2024jd043218
Authors: E. M. Waxman, R.‐S. Gao, T. Thornberry, R. McLaughlin, G. Novak, E. Atlas, S. Schauffler, V. Treadaway, K. Smith, R. Lueb, R. Hendershot, T. Campos, G. Wolfe, J. M. St. Clair, E. Delaria, D. Anderson, S. Viciani, F. D’Amato, G. Bianchini, M. Barucci, C. Gurganus, L. Iraci, J. Podolske, G. Diskin, Y. Choi, J. DiGangi, T. P. Bui, J. Dean‐Day, C. Gatebe, L. L. Pan, A. Rollins
Institutions: Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, NOAA Chemical Sciences Laboratory, University of Miami, NSF National Center for Atmospheric Research, NSF NCAR Atmospheric Chemistry Observations & Modeling, Ames Research Center, Goddard Space Flight Center, University of Maryland, Baltimore County, National Institute of Optics, National Research Council, Langley Research Center, Bay Area Environmental Research Institute
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $4,070
Awards: G1228214836, G1335240794, The Management and Operation of the National Center for Atmoshperic Research (NCAR), G2802604304, G3230025638, G3664948245, G3941450307, G40072227, Collaborative Research: Analyses, Measurements and Modeling in Support of the Asian Monsoon Chemical and Climate Impact Project (ACCLIP), G6006804047, G6431876418, G7198630863, G7611606887, G8964276348
OpenAlex ID: W4414820469