AUTHOR=Kulmala Markku , Junninen Heikki , Dada Lubna , Salma Imre , Weidinger Tamás , Thén Wanda , Vörösmarty Máté , Komsaare Kaupo , Stolzenburg Dominik , Cai Runlong , Yan Chao , Li Xinyang , Deng Chenjuan , Jiang Jingkun , Petäjä Tuukka , Nieminen Tuomo , Kerminen Veli-Matti TITLE=Quiet New Particle Formation in the Atmosphere JOURNAL=Frontiers in Environmental Science VOLUME=Volume 10 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2022.912385 DOI=10.3389/fenvs.2022.912385 ISSN=2296-665X ABSTRACT=

Atmospheric new particle formation (NPF) has been observed to take place in practice all around the world. In continental locations, typically about 10–40% of the days are so-called NPF event days characterized by a clear particle formation and growth that continue for several hours, occurring mostly during daytime. The other days are either non-event days, or days for which it is difficult to decide whether NPF had occurred or not. Using measurement data from several locations (Hyytiälä, Järvselja, and near-city background and city center of Budapest), we were able to show that NPF tends to occur also on the days traditionally characterized as non-event days. One explanation is the instrument sensitivity towards low number concentrations in the sub-10 nm range, which usually limits our capability to detect such NPF events. We found that during such days, particle formation rates at 6 nm were about 2–20% of those observed during the traditional NPF event days. Growth rates of the newly formed particles were very similar between the traditional NPF event and non-event days. This previously overlooked phenomenon, termed as quiet NPF, contributes significantly to the production of secondary particles in the atmosphere.