Yafang Cheng’s scientific research has made several breakthroughs and transformative advances in the mechanistic understanding of atmospheric processes, especially on atmospheric aerosols and their effects on air quality, health and climate. She discovered novel mechanisms and developed new theories of reactive nitrogen chemistry that reshaped the scientific understanding of haze formation and nitrogen cycling. Her work revealed how the extreme haze events in northern China can be explained by multiphase oxidation reactions in aerosol water and developed a multiphase buffer theory to explain atmospheric aerosol acidity and the sustainability and high effectiveness of multiphase oxidation. Cheng and her group have developed new instruments and techniques to probe physical and chemical properties of aerosol nanoparticles. With these advanced techniques and in-depth molecular dynamics simulations, she was the first to reveal that particle size can strongly alter the characteristic concentration of phase separation in mixed systems, resembling the influence of temperature. Cheng’s research on aerosol climate impact is also dealing with black carbon (BC) as one of the most important short-lived climate warming agents. To obtain a global climatology of BC aerosols, she initiated and continues to lead the CARIBIC-SP2 (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container–Single Particle Soot Photometer) and Eugen Seibold-SP2 projects, where she measures BC aerosol concentration and mixing state on board a Lufthansa passenger aircraft and a sailing yacht for ocean research. In this way, she has collected the largest ever BC measurement data set from over 1,000 flight hours at high-altitude and about 2,000 sailing hours in remote marine environments, where data are particularly important for evaluating the climate effects of BC aerosols. Her systematic investigations provide unique insights and demonstrate the importance of the radiative effects of light-absorbing aerosols and wildfire emissions on cloud formation and regional climate in the Amazon, Southeast Asia and the Arctic. Cheng has successfully demonstrated how a better physicochemical understanding of Earth system processes enables the development and implementation of effective strategies to protect human health and mitigate air pollution and climate change in the Anthropocene. Moreover, she was able to improve the scientific understanding of SARS-CoV-2 aerosol transmission and to quantify the effectiveness of masks and other protective measures with key policy implications in combatting the COVID-19 pandemic. Yafang Cheng has also demonstrated exceptional leadership and provided outstanding service to science and society. Her honors include the Science Breakthrough Award in Physical Sciences of the Falling Walls Foundation (2021) and the Schmauss Award of the German Association for Aerosol Research (2020). — Jos Lelieveld The Max Planck Institute for Chemistry Mainz, Germany — Renyi Zhang Texas A&M University College Station, Texas

Thank you, Renyi and Jos, for the nomination, your very kind citation and great support. Many thanks to AGU and the award committee. I am deeply honored and grateful to receive this medal, in memory of a woman who has greatly advanced atmospheric sciences and who is still inspiring and encouraging our community today. I want to acknowledge so many people that got me here. Max Planck Institute for Chemistry, everybody at MPIC, you are the reason I love to stay in Mainz. Uli Poschl, Andi Andreae, the relationship of trust and friendship over these many years are priceless. University of Iowa and Leibniz Institute, Greg Carmichael, Ali Wiedensohler, Jost Heintzenberg, I still remember the scene when we first met. Peking University, my mentor Yuanhang Zhang, and the lake and tower on the beautiful campus. There are too many names that I should mention, but allow me to single out a few. Susan Trumbore, Markku Kulmala, Katharina Kohse-Höinghaus, Doug Worsnorp, Andreas Wahner, Sjaak Slanina, I deeply appreciate your support. Paul Crutzen, Kurt Binder, truly an honor to work with you. Your dignity and integrity in research and in educating young generations will always encourage me to face challenges and difficult moments. Thank you! I also want to give special thanks to all my former and current group members. You are amazing. I wouldn’t be here without our joint adventures on the airplane, over the ocean, in the rainforest and in the virtual digital Earth. In particular, Guangjie, Nan, Zhibin, Siwen, Meng, Qing, Guo, Ruijing, Chaoqun and many more, your enthusiasm and strong dedication also motivate me and the whole team. I would also like to thank my parents and my husband; none of this would be possible without you, and to my son, I love you dearly, and you have already started to inspire me. This is a world that we are collectively feeling and experiencing. To face the grand challenge of climate change and air pollution, a global effort is needed. This is our time, our responsibility and our chance to work together and make a difference. Thank you! — Yafang Cheng Minerva Independent Research Group, Max Planck Institute for Chemistry Mainz, Germany