Marine upper-tropospheric rapid particle formation dominated by methanesulfonic acid

• 成果类型: Article
• 署名作者: Ning, An; Mao, Lizhuo; Zhao, Bin; Zu, Haotian; Shen, Jiewen; Zhao, Yonggui; Li, Jing; Deng, Xiucong; Liu, Ling; Zhang, Haijie; Francisco, Joseph S.; Wang, Shuxiao; Zhang, Xiuhui
• 署名单位: Beijing Institute of Technology; Tsinghua University; University of Zurich; Chinese Research Academy of Environmental Sciences; University of Pennsylvania; University of Pennsylvania
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2606521123
• 发表日期: 2026-06-02
• 页码: e2606521123
• 关键词: marine aerosol; new particle formation; nucleation mechanism; methanesulfonic acid; upper troposphere; LONG-RANGE TRANSPORT; sulfuric-acid; oxidation-products; DIMETHYL SULFIDE; nucleation; ammonia; isoprene; amine

摘要

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 (H2SO4)-ammonia (NH3) nucleation rates by 1 to 3 orders of magnitude, far surpassing the well-established nitric acid (HNO3)-H2SO4-NH3 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 H2SO4-MSA-NH3 nucleation pathway dominates the upper-tropospheric NPF over the Pacific, Atlantic, and Indian Oceans. Notably, this pathway contributes similar to 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) (similar to 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.