Stratospheric air intrusions promote global-scale new particle formation

• 成果类型: Article
• 署名作者: Zhang, Jiaoshi; Gong, Xianda; Crosbie, Ewan; Diskin, Glenn; Froyd, Karl; Hall, Samuel; Kupc, Agnieszka; Moore, Richard; Peischl, Jeff; Rollins, Andrew; Schwarz, Joshua; Shook, Michael; Thompson, Chelsea; Ullmann, Kirk; Williamson, Christina; Wisthaler, Armin; Xu, Lu; Ziemba, Luke; Brock, Charles A.; Wang, Jian
• 署名单位: Washington University (WUSTL); National Aeronautics & Space Administration (NASA); NASA Langley Research Center; Science Systems & Applications Inc; University of Colorado System; University of Colorado Boulder; National Oceanic Atmospheric Admin (NOAA) - USA; National Center Atmospheric Research (NCAR) - USA; University of Vienna; Finnish Meteorological Institute; University of Helsinki; University of Innsbruck; University of Oslo
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-12450
• DOI: 10.1126/science.adn2961
• 发表日期: 2024-07-12
• 页码: 210-216
• 关键词: cloud condensation nuclei; troposphere exchange; mixing processes; sulfur-dioxide; north-atlantic; nitrous-oxide; aerosol; nucleation; transport; ozone

摘要

New particle formation in the free troposphere is a major source of cloud condensation nuclei globally. The prevailing view is that in the free troposphere, new particles are formed predominantly in convective cloud outflows. We present another mechanism using global observations. We find that during stratospheric air intrusion events, the mixing of descending ozone-rich stratospheric air with more moist free tropospheric background results in elevated hydroxyl radical (OH) concentrations. Such mixing is most prevalent near the tropopause where the sulfur dioxide (SO2) mixing ratios are high. The combination of elevated SO2 and OH levels leads to enhanced sulfuric acid concentrations, promoting particle formation. Such new particle formation occurs frequently and over large geographic regions, representing an important particle source in the midlatitude free troposphere.