Marine upper-tropospheric rapid particle formation dominated by methanesulfonic acid
7 affiliations
- 1State Key Laboratory of Environment Characteristics and Effects for Near-space, Key Laboratory of Cluster Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Beijing Institute of Technology
- 2State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex
- 3State Key Laboratory of Regional Environment and Sustainability, School of Environment, Tsinghua University
- 4Department of Chemistry, University of Zurich
- 5State Key Laboratory of Environmental Benchmarking and Risk Assessment, Chinese Research Academy of Environmental Sciences
- 6Department of Chemistry, University of Pennsylvania
- 7Department of Earth and Environmental Science, University of Pennsylvania
Abstract
New particle formation (NPF) in the marine upper troposphere sustains one of the largest global aerosol reservoirs that seeds cloud condensation nuclei in the lower troposphere, with far-reaching implications for Earth’s radiative balance and climate. However, the underlying NPF mechanisms remain elusive, constituting a major uncertainty in climate projections. Here, we show that methanesulfonic acid (MSA), long considered only as a key boundary-layer precursor, dominates upper-tropospheric NPF across major oceans. Quantum-chemical and cluster dynamics simulations reveal that MSA enhances sulfuric acid (H 2 SO 4 )–ammonia (NH 3 ) nucleation rates by 1 to 3 orders of magnitude, far surpassing the well-established nitric acid (HNO 3 )–H 2 SO 4 –NH 3 mechanism, owing to stronger intracluster hydrogen bonds and low temperatures that stabilize clusters and render nucleation nearly barrierless. Further global three-dimensional modeling constrained by field measurements confirms that the proposed H 2 SO 4 –MSA–NH 3 nucleation pathway dominates the upper-tropospheric NPF over the Pacific, Atlantic, and Indian Oceans. Notably, this pathway contributes ~40% of global nucleation-induced Aitken- and accumulation-mode aerosols at 0.5 to 4 km altitudes, where most cloud water resides, and yields a net top-of-atmosphere radiation forcing of −1.75 W m −2 (~68% of the nucleation-induced response). This study offers a detailed mechanistic insight into marine upper-tropospheric NPF and improves representation of aerosol–cloud interactions, thereby reducing uncertainties in global climate projections.
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BibTeX
@article{an2026marine,
title = {{Marine upper-tropospheric rapid particle formation dominated by methanesulfonic acid}},
author = {Ning An and L.Y. Mao and Bin Zhao and Haotian Zu and Jiewen Shen and Yonggui Zhao and Jing Li and Xiucong Deng and Ling Liu and Haijie Zhang and Joseph S. Francisco and S S Wang and Xiuhui Zhang},
journal = {Proceedings of the National Academy of Sciences},
year = {2026},
month = may,
doi = {10.1073/pnas.2606521123},
url = {https://doi.org/10.1073/pnas.2606521123},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Marine upper-tropospheric rapid particle formation dominated by methanesulfonic acid
AU - Ning An
AU - L.Y. Mao
AU - Bin Zhao
AU - Haotian Zu
AU - Jiewen Shen
AU - Yonggui Zhao
AU - Jing Li
AU - Xiucong Deng
AU - Ling Liu
AU - Haijie Zhang
AU - Joseph S. Francisco
AU - S S Wang
AU - Xiuhui Zhang
PY - 2026
DA - 2026/05/29
JO - Proceedings of the National Academy of Sciences
DO - 10.1073/pnas.2606521123
UR - https://doi.org/10.1073/pnas.2606521123
AB - New particle formation (NPF) in the marine upper troposphere sustains one of the largest global aerosol reservoirs that seeds cloud condensation nuclei in the lower troposphere, with far-reaching implications for Earth’s radiative balance and climate. However, the underlying NPF mechanisms remain elusive, constituting a major uncertainty in climate projections. Here, we show that methanesulfonic acid (MSA), long considered only as a key boundary-layer precursor, dominates upper-tropospheric NPF across major oceans. Quantum-chemical and cluster dynamics simulations reveal that MSA enhances sulfuric acid (H 2 SO 4 )–ammonia (NH 3 ) nucleation rates by 1 to 3 orders of magnitude, far surpassing the well-established nitric acid (HNO 3 )–H 2 SO 4 –NH 3 mechanism, owing to stronger intracluster hydrogen bonds and low temperatures that stabilize clusters and render nucleation nearly barrierless. Further global three-dimensional modeling constrained by field measurements confirms that the proposed H 2 SO 4 –MSA–NH 3 nucleation pathway dominates the upper-tropospheric NPF over the Pacific, Atlantic, and Indian Oceans. Notably, this pathway contributes ~40% of global nucleation-induced Aitken- and accumulation-mode aerosols at 0.5 to 4 km altitudes, where most cloud water resides, and yields a net top-of-atmosphere radiation forcing of −1.75 W m −2 (~68% of the nucleation-induced response). This study offers a detailed mechanistic insight into marine upper-tropospheric NPF and improves representation of aerosol–cloud interactions, thereby reducing uncertainties in global climate projections.
SN - 0027-8424
SN - 1091-6490
ER -