Articles | Volume 26, issue 13
https://doi.org/10.5194/acp-26-9809-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-26-9809-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
13 Jul 2026
Research article |
| 13 Jul 2026
| 13 Jul 2026
Development of iron-mediated molecular chlorine chemistry in GEOS-Chem: model description, evaluation and global atmospheric implication
Jing Chen
Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
Xianyi Sun
Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
Chuang Qin
Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
Jie Li
Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
Qianjie Chen
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong SAR 999077, China
Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
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Shengjin Xie, Xuelei Zhang, Aijun Xiu, Hong Qi, Shengrui Tong, Qianjie Chen, Chao Gao, Hongmei Zhao, Shichun Zhang, Stephen Dauda Yabo, Yiming Liu, Siting Li, and Mengduo Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2025-5338, https://doi.org/10.5194/egusphere-2025-5338, 2026
This preprint is open for discussion and under review for The Cryosphere (TC).
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This study examines how snow-covered surfaces affect air pollution in Northeast China. Using numerical simulations, we explore chlorine-related chemical reactions that generate reactive species, enhancing fine particles and ozone. Results show that snow-surface reactions drive nighttime pollutant accumulation and notably improve model performance, providing new insights into how snow and surface chemistry influence regional air quality.
Zhouxing Zou, Tianshu Chen, Qianjie Chen, Weihang Sun, Shichun Han, Zhuoyue Ren, Xinyi Li, Wei Song, Aoqi Ge, Qi Wang, Xiao Tian, Chenglei Pei, Xinming Wang, Yanli Zhang, and Tao Wang
Atmos. Chem. Phys., 25, 8147–8161, https://doi.org/10.5194/acp-25-8147-2025, https://doi.org/10.5194/acp-25-8147-2025, 2025
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We measured ambient OH and HO2* (HO2 and contribution from RO2, organic peroxyl radicals) concentrations at a subtropical rural site and compared our observations with model results. During warm periods, the model overestimated concentrations of OH and HO2, leading to overestimation of ozone and nitric acid production. Our findings highlight the need to better understand how OH and HO2 are formed and removed, which is important for accurate air quality and climate predictions.
Ursula A. Jongebloed, Jacob I. Chalif, Linia Tashmim, William C. Porter, Kelvin H. Bates, Qianjie Chen, Erich C. Osterberg, Bess G. Koffman, Jihong Cole-Dai, Dominic A. Winski, David G. Ferris, Karl J. Kreutz, Cameron P. Wake, and Becky Alexander
Atmos. Chem. Phys., 25, 4083–4106, https://doi.org/10.5194/acp-25-4083-2025, https://doi.org/10.5194/acp-25-4083-2025, 2025
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Marine phytoplankton emit dimethyl sulfide (DMS), which forms methanesulfonic acid (MSA) and sulfate. MSA concentrations in ice cores decreased over the industrial era, which has been attributed to pollution-driven changes in DMS chemistry. We use a model to investigate DMS chemistry compared to observations of DMS, MSA, and sulfate. We find that modeled DMS, MSA, and sulfate are influenced by pollution-sensitive oxidant concentrations, characterization of DMS chemistry, and other variables.
Linia Tashmim, William C. Porter, Qianjie Chen, Becky Alexander, Charles H. Fite, Christopher D. Holmes, Jeffrey R. Pierce, Betty Croft, and Sakiko Ishino
Atmos. Chem. Phys., 24, 3379–3403, https://doi.org/10.5194/acp-24-3379-2024, https://doi.org/10.5194/acp-24-3379-2024, 2024
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Dimethyl sulfide (DMS) is mostly emitted from ocean surfaces and represents the largest natural source of sulfur for the atmosphere. Once in the atmosphere, DMS forms stable oxidation products such as SO2 and H2SO4, which can subsequently contribute to airborne particle formation and growth. In this study, we update the DMS oxidation mechanism in the chemical transport model GEOS-Chem and describe resulting changes in particle growth as well as the overall global sulfur budget.
Zhouxing Zou, Qianjie Chen, Men Xia, Qi Yuan, Yi Chen, Yanan Wang, Enyu Xiong, Zhe Wang, and Tao Wang
Atmos. Chem. Phys., 23, 7057–7074, https://doi.org/10.5194/acp-23-7057-2023, https://doi.org/10.5194/acp-23-7057-2023, 2023
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We present OH observation and model simulation results at a coastal site in Hong Kong. The model predicted the OH concentration under high-NOx well but overpredicted it under low-NOx conditions. This implies an insufficient understanding of OH chemistry under low-NOx conditions. We show evidence of missing OH sinks as a possible cause of the overprediction.
Qianjie Chen, Jessica A. Mirrielees, Sham Thanekar, Nicole A. Loeb, Rachel M. Kirpes, Lucia M. Upchurch, Anna J. Barget, Nurun Nahar Lata, Angela R. W. Raso, Stephen M. McNamara, Swarup China, Patricia K. Quinn, Andrew P. Ault, Aaron Kennedy, Paul B. Shepson, Jose D. Fuentes, and Kerri A. Pratt
Atmos. Chem. Phys., 22, 15263–15285, https://doi.org/10.5194/acp-22-15263-2022, https://doi.org/10.5194/acp-22-15263-2022, 2022
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During a spring field campaign in the coastal Arctic, ultrafine particles were enhanced during high wind speeds, and coarse-mode particles were reduced during blowing snow. Calculated periods blowing snow were overpredicted compared to observations. Sea spray aerosols produced by sea ice leads affected the composition of aerosols and snowpack. An improved understanding of aerosol emissions from leads and blowing snow is critical for predicting the future climate of the rapidly warming Arctic.
William F. Swanson, Chris D. Holmes, William R. Simpson, Kaitlyn Confer, Louis Marelle, Jennie L. Thomas, Lyatt Jaeglé, Becky Alexander, Shuting Zhai, Qianjie Chen, Xuan Wang, and Tomás Sherwen
Atmos. Chem. Phys., 22, 14467–14488, https://doi.org/10.5194/acp-22-14467-2022, https://doi.org/10.5194/acp-22-14467-2022, 2022
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Radical bromine molecules are seen at higher concentrations during the Arctic spring. We use the global model GEOS-Chem to test whether snowpack and wind-blown snow sources can explain high bromine concentrations. We run this model for the entire year of 2015 and compare results to observations of bromine from floating platforms on the Arctic Ocean and at Utqiaġvik. We find that the model performs best when both sources are enabled but may overestimate bromine production in summer and fall.
Kathryn D. Kulju, Stephen M. McNamara, Qianjie Chen, Hannah S. Kenagy, Jacinta Edebeli, Jose D. Fuentes, Steven B. Bertman, and Kerri A. Pratt
Atmos. Chem. Phys., 22, 2553–2568, https://doi.org/10.5194/acp-22-2553-2022, https://doi.org/10.5194/acp-22-2553-2022, 2022
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N2O5 uptake by chloride-containing surfaces produces ClNO2, which photolyzes, producing NO2 and highly reactive Cl radicals that impact air quality. In the inland urban atmosphere, ClNO2 was elevated during lower air turbulence and over snow-covered ground, from snowpack ClNO2 production. N2O5 and ClNO2 levels were lowest, on average, during rainfall and fog because of scavenging, with N2O5 scavenging by fog droplets likely contributing to observed increased particulate nitrate concentrations.
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Short summary
By incorporating an iron-mediated molecular chlorine (Cl2) formation pathway into the GEOS-Chem global atmospheric chemistry transport model, simulated surface Cl2 concentrations align better with observations. Reactive chlorine species increase substantially, thereby altering atmospheric oxidative capacity. Stronger oxidation elevates PM2.5 levels in polluted regions, especially in winter, underscoring the need to consider iron–halogen coupling chemistry in future air-quality mitigation.
By incorporating an iron-mediated molecular chlorine (Cl2) formation pathway into the GEOS-Chem...
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