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ACP - recent papers

Combined list of the recent articles of the journal Atmospheric Chemistry and Physics and the recent discussion forum Atmospheric Chemistry and Physics Discussions
  • Injection near the stratopause mitigates the stratospheric side effects of sulfur-based climate intervention
    Injection near the stratopause mitigates the stratospheric side effects of sulfur-based climate intervention Pengfei Yu, Yifeng Peng, Karen H. Rosenlof, Ru-Shan Gao, Robert W. Portmann, Martin Ross, Eric Ray, Jianchun Bian, Simone Tilmes, and Owen B. Toon Atmos. Chem. Phys., 25, 18449–18460, https://doi.org/10.5194/acp-25-18449-2025, 2025 Injecting sulfur dioxide at 50 km – near the stratopause – offers a far safer and more effective climate intervention than conventional 25 km injection. Rapid downward–poleward transport distributes aerosols across 20–30 km, halving tropical stratospheric warming, reducing ozone recovery delays from decades to about 5 years, and enhancing global and polar cooling by over 20 %, while better preserving Arctic sea ice.

  • Why is height-dependent mixing observed in stratocumulus clouds?
    Why is height-dependent mixing observed in stratocumulus clouds? Zeen Zhu, Fan Yang, Steven Krueger, and Yangang Liu Atmos. Chem. Phys., 25, 18461–18474, https://doi.org/10.5194/acp-25-18461-2025, 2025 To better understand cloud behavior, we used model simulation to study how the air mix in clouds. Our results show that the pattern of mixing seen from aircraft measurements may not reflect the true mixing process happening inside clouds. This result suggests that care is needed when using aircraft data to study the cloud mixing process and that new ways of observing clouds could offer clearer insights.

  • Influence of sudden stratospheric warming with elevated stratopause on the hydroxyl in the polar middle atmosphere
    Influence of sudden stratospheric warming with elevated stratopause on the hydroxyl in the polar middle atmosphere Jin Hu, Sheng-Yang Gu, Yusong Qin, Yuxuan Liu, and Yafei Wei Atmos. Chem. Phys., 25, 18431–18447, https://doi.org/10.5194/acp-25-18431-2025, 2025 This paper focuses on the response of the polar hydroxyl layer in the mesosphere to Arctic sudden stratospheric warming events with an elevated stratopause, revealing significant phase-dependent variations in hydroxyl distribution driven by gravity wave drag changes. These findings enhance our understanding of vertical and dynamical-photochemical coupling in the middle and upper atmosphere, which also offer valuable implications for the upper atmospheric sounding and modeling.

  • Challenges and benefits of using NOx as a quantitative proxy for fossil fuel CO2 in an urban area based on radiocarbon measurements
    Challenges and benefits of using NOx as a quantitative proxy for fossil fuel CO2 in an urban area based on radiocarbon measurements Hannes Juchem, Fabian Maier, Ingeborg Levin, Armin Jordan, Denis Pöhler, Claudius Rosendahl, Julian Della Coletta, Susanne Preunkert, and Samuel Hammer Atmos. Chem. Phys., 25, 18373–18388, https://doi.org/10.5194/acp-25-18373-2025, 2025 This study explores how in situ NOx observations can be used to estimate fossil fuel CO2 (ffCO2) enhancements in an urban context, based on radiocarbon measurements. Even with a simple approach to account for atmospheric chemistry and ratio variability, a strong correlation could be observed, allowing the construction of a high temporal resolution NOx-based ffCO2 record with uncertainties comparable to the use of CO as proxy. Comparisons with independent records show good agreement between them.

  • Origin, transport and processing of organic aerosols at different altitudes in coastal Mediterranean urban areas
    Origin, transport and processing of organic aerosols at different altitudes in coastal Mediterranean urban areas Clara Jaén, Mireia Udina, Roy Harrison, Joan O. Grimalt, and Barend L. Van Drooge Atmos. Chem. Phys., 25, 18389–18407, https://doi.org/10.5194/acp-25-18389-2025, 2025 Distance changes air pollution in a city, but so does the time of the day and the year, due to varying emission sources and weather conditions. These changes were studied at ground level and 400 meters above the city, and showed that wood burning affected the air quality in winter, while products of atmospheric reaction processes dominated the air in summer. Traffic emissions arrive to the elevated site during the day, while they were trapped at lower level in the night.