Research Article
Time Integrated Radiative Forcing from North American NOX Emissions: Climate Effect over 20- and 100-year Time Scales
Richard Damoah*
Issue:
Volume 10, Issue 1, June 2026
Pages:
1-12
Received:
21 February 2026
Accepted:
18 March 2026
Published:
30 March 2026
Abstract: The distribution of tropospheric ozone (O3) globally depends on the emission of precursors (e.g., NOx), chemistry, and transport. In this study, we quantify the response of radiative forcing over 20- and 100-year time scales, to O3 and methane (CH4) perturbations caused by a marginal increase (0.1 Tg N) in anthropogenic emissions of NOx in January and July from 21 (10° × 10° grid) geographical locations in North America. Changes in the perturbations have been calculated with the global climate-chemistry transport model STOCHEM. Addition of NOx emissions led to an initial increase in global O3 burdens up to 0.9 Tg, which decayed after 4 months. Global CH4 burdens decreased (by increasing OH) by up to –0.7 Tg and decayed gradually after 6 months. Global radiative forcings resulting from the regional emission increases were calculated, accounting for changes in both O3 (using an offline radiation code) and CH4 (using a simple conversion of 0.37 mW m⁻² ppb⁻1, assuming that CH4 is well mixed in the atmosphere). Our results revealed that O3-induced time-integrated radiative forcings exhibit both positive (initial) and negative (long-term) phases in the two (20- and 100-year) time horizons. For the positive phase, both the 20- and 100-year time periods peaked at 0.454 mW m⁻² yr; however, for the negative phase, the 20-year peaked at –0.246 mW m⁻² yr and the 100-year peaked at –0.300 mW m⁻² yr. CH4, on the other hand, showed a single negative phase which peaked at –1.070 mW m⁻² yr for the 20-year time period and –1.302 mW m⁻² yr for the 100-year time period. The total net radiative forcings (assuming a linear additive for relatively small perturbations) of the CH4 term and the two O3 terms over a 100-year time period from all 21 locations produce a net climate cooling effect (negative forcings), irrespective of the season of the emission pulses. However, over a 20-year time period in winter, some emission pulses at low latitudes produce a net climate warming effect (positive forcings). Both the O3 and CH4 burdens and the associated radiative forcings depend strongly on the geographical location as well as the season of the emission pulses. They are most sensitive to emissions from low latitudes and least sensitive to emissions from mid-latitudes and high latitudes.
Abstract: The distribution of tropospheric ozone (O3) globally depends on the emission of precursors (e.g., NOx), chemistry, and transport. In this study, we quantify the response of radiative forcing over 20- and 100-year time scales, to O3 and methane (CH4) perturbations caused by a marginal increase (0.1 Tg N) in anthropogenic emissions of NOx in January ...
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Review Article
Photochemical Dynamics of Surface Ozone (O3), Carbon Monoxide (CO), and Nitrogen Oxides (NOx): Implications for Air Pollution, Health and Climate
Issue:
Volume 10, Issue 1, June 2026
Pages:
13-24
Received:
26 February 2026
Accepted:
19 March 2026
Published:
7 April 2026
DOI:
10.11648/j.ijaos.20261001.12
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Abstract: Atmospheric trace gases such as ozone (O3), carbon monoxide (CO), and nitrogen oxides (NO and NO2, collectively termed NOx) play a central role in tropospheric photochemistry and strongly influence air quality, climate forcing, and ecosystem health. This manuscript explores the current understanding of the sources, chemical transformation pathways, and environmental impacts of these trace gases by integrating from observational studies and atmospheric modeling research. The literature was compiled through a structured review of peer-reviewed research published in science journals, with emphasis on recent advances in photochemical mechanisms, boundary layer dynamics and regional air pollution processes. Particular attention is given to nonlinear O3 formation regimes, radical chemistry involving volatile organic compounds (VOCs), and the interactions between trace gases and climate processes. This manuscript highlights how the balance between NOx and VOC emissions determines O3 production efficiency in different atmospheric environments, ranging from NOx limited rural regions to VOC limited urban areas. Regional perspectives from South Asia illustrate how rapid urbanization, biomass burning, and meteorological variability influence trace gas distributions. The analysis identifies major knowledge gaps related to radical chemistry uncertainties, climate–chemistry feedback mechanisms, and the integration of observational networks with chemical transport models. Improved monitoring strategies and advanced modeling approaches are essential for developing effective air quality management policies and understanding the evolving role of trace gases in the Earth’s climate system.
Abstract: Atmospheric trace gases such as ozone (O3), carbon monoxide (CO), and nitrogen oxides (NO and NO2, collectively termed NOx) play a central role in tropospheric photochemistry and strongly influence air quality, climate forcing, and ecosystem health. This manuscript explores the current understanding of the sources, chemical transformation pathways,...
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