Opinion: A paradigm shift in investigating the general characteristics of atmospheric new particle formation using field observations

Abstract

Abstract. Atmospheric new particle formation (NPF) and associated production of secondary particulate matter dominate aerosol particle number concentrations and submicron particle mass loadings in many environments globally. Our recent investigations show that atmospheric NPF produces a significant amount of particles on days when no clear NPF event has been observed/identified. Furthermore, it has been observed in different environments all around the world that growth rates of nucleation mode particles vary little, usually much less than the measured concentrations of condensable vapors. It has also been observed that the local clustering, which in many cases acts as a starting point of regional new particle formation (NPF), can be described with the formation of intermediate ions at the smallest sizes. These observations, together with a recently developed ranking method, lead us to propose a paradigm shift in atmospheric NPF investigations. In this opinion paper, we will summarize the traditional approach of describing atmospheric NPF and describe an alternative method, covering both particle formation and initial growth. The opportunities and remaining challenges offered by the new approach are discussed.

New Particle Formation dynamics in the central Andes: Contrasting urban and mountain-top environments

“…Dal Maso et al, 2005;Kulmala et al, 2012;Dada et al, 2018), but this binary approach often misclassifies weak events and non-regional phenomena, limiting further analyses such as growth and formation rates. Kulmala et al (2024) proposed deriving a probability distribution for NPF intensity across all observed days, using nanoparticle ranking analysis (Aliaga et al, 2023) to produce a daily metric indicative of NPF intensity. This metric, which focuses on the daily maximum minus background particle concentration within the nucleation mode, correlates higher values with increased formation rates and event probabilities.…”

“…This metric, which focuses on the daily maximum minus background particle concentration within the nucleation mode, correlates higher values with increased formation rates and event probabilities. Additionally, grouping days by shared characteristics, such as chemical environment, season, or air mass origin, as demonstrated by Kulmala et al ( , 2024, helps identify emerging patterns and mitigates observational noise, leading to more accurate estimations of metrics like GR.…”

“…Another significant challenge in the study of NPF is identifying days on which NPF events are observed (Kulmala et al, 2024). Traditionally these are classified into event days, non-event days, and undefined days (e.g.…”