美国卡内基梅隆大学Kulmala, Markku团队报道了协同HNO3–H2SO4–NH3对流层上部粒子形成。相关研究成果发表在2022年5月18日出版的《自然》。
高空自由对流层中新粒子的形成是云凝聚核（CCN）的主要全球来源。然而，驱动该过程的前驱体蒸汽还没有很好的理解。在CERN云室对流层上部条件下进行的实验表明，硝酸、硫酸和氨协同形成粒子，其速度比三种成分中任何两种的速度都快几个数量级。这一机制的重要性取决于氨的可用性，以前认为氨在对流过程中可以被云滴有效清除。然而，最近在亚洲季风区的对流层上部观察到了令人惊讶的高浓度氨和硝酸铵。一旦颗粒形成，氨和丰富的硝酸单独的共缩合就足以驱动快速生长到CCN大小，只有微量硫酸盐。
此外，测量表明，这些CCN也是与沙漠尘埃相当的高效冰核粒子。研究模型模拟证实，在亚洲季风期间，氨在高空有效对流，推动对流层上部的多酸HNO3–H2SO4–NH3快速成核，并产生遍布中纬度北半球的冰核粒子。
附：英文原文
Title: Synergistic HNO3–H2SO4–NH3 upper tropospheric particle formation
Author: Wang, Mingyi, Xiao, Mao, Bertozzi, Barbara, Marie, Guillaume, Rrup, Birte, Schulze, Benjamin, Bardakov, Roman, He, Xu-Cheng, Shen, Jiali, Scholz, Wiebke, Marten, Ruby, Dada, Lubna, Baalbaki, Rima, Lopez, Brandon, Lamkaddam, Houssni, Manninen, Hanna E., Amorim, Antnio, Ataei, Farnoush, Bogert, Pia, Brasseur, Zo, Caudillo, Luca, De Menezes, Louis-Philippe, Duplissy, Jonathan, Ekman, Annica M. L., Finkenzeller, Henning, Carracedo, Loc Gonzalez, Granzin, Manuel, Guida, Roberto, Heinritzi, Martin, Hofbauer, Victoria, Hhler, Kristina, Korhonen, Kimmo, Krechmer, Jordan E., Krten, Andreas, Lehtipalo, Katrianne, Mahfouz, Naser G. A., Makhmutov, Vladimir, Massab, Dario, Mathot, Serge, Mauldin, Roy L., Mentler, Bernhard, Mller, Tatjana, Onnela, Antti, Petj, Tuukka, Philippov, Maxim, Piedehierro, Ana A., Pozzer, Andrea, Ranjithkumar, Ananth, Schervish, Meredith, Schobesberger, Siegfried, Simon, Mario, Stozhkov, Yuri, Tom, Antnio, Umo, Nsikanabasi Silas, Vogel, Franziska, Wagner, Robert, Wang, Dongyu S., Weber, Stefan K., Welti, Andr, Wu, Yusheng, Zauner-Wieczorek, Marcel, Sipil, Mikko, Winkler, Paul M., Hansel, Armin, Baltensperger, Urs, Kulmala, Markku
Issue&Volume: 2022-05-18
Abstract: New particle formation in the upper free troposphere is a major global source of cloud condensation nuclei (CCN)1,2,3,4. However, the precursor vapours that drive the process are not well understood. With experiments performed under upper tropospheric conditions in the CERN CLOUD chamber, we show that nitric acid, sulfuric acid and ammonia form particles synergistically, at rates that are orders of magnitude faster than those from any two of the three components. The importance of this mechanism depends on the availability of ammonia, which was previously thought to be efficiently scavenged by cloud droplets during convection. However, surprisingly high concentrations of ammonia and ammonium nitrate have recently been observed in the upper troposphere over the Asian monsoon region5,6. Once particles have formed, co-condensation of ammonia and abundant nitric acid alone is sufficient to drive rapid growth to CCN sizes with only trace sulfate. Moreover, our measurements show that these CCN are also highly efficient ice nucleating particles—comparable to desert dust. Our model simulations confirm that ammonia is efficiently convected aloft during the Asian monsoon, driving rapid, multi-acid HNO3–H2SO4–NH3 nucleation in the upper troposphere and producing ice nucleating particles that spread across the mid-latitude Northern Hemisphere.
DOI: 10.1038/s41586-022-04605-4
Source: https://www.nature.com/articles/s41586-022-04605-4