Towards a concentration closure of sub-6 nm aerosol particles and sub-3 nm atmospheric clusters

Markku Kulmala,Dominik Stolzenburg,Lubna Dada,Runlong Cai,Jenni Kontkanen,Chao Yan,Juha Kangasluoma,Lauri R Ahonen,Loïc Gonzalez-Carracedo,Juha Sulo,Santeri Tuovinen,Chenjuan Deng,Yiran Li,Katrianne Lehtipalo,Kari E.J Lehtinen,Tuukka Petäjä,Paul M Winkler,Jingkun Jiang,Veli-Matti Kerminen

doi:10.1016/j.jaerosci.2021.105878

Abstract

Atmospheric clusters play a key role in atmospheric new particle formation and they are a sensitive indicator for atmospheric chemistry. Both the formation and loss of atmospheric clusters include a complex set of interlinked physical and chemical processes, and therefore their dynamics is highly non-linear. Here we derive a set of simple equations to estimate the atmospheric cluster concentrations in size ranges of 1.5–2 nm and 2–3 nm as well as 3–6 nm aerosol particles. We compared the estimated concentrations with measured ones both in a boreal forest site (the SMEAR II station in Hyytiälä, Finland) and in an urban site (the AHL/BUCT station in Beijing, China). We made this comparison first for 3–6 nm particles, since in this size range observations are more reliable than at smaller sizes, and then repeated it for the 2–3 nm size range. Finally, we estimated cluster concentrations in the 1.5–2 nm size range. Our main finding is that the present observations are able to detect a major fraction of existing atmospheric clusters.

Highlights

New particle formation (NPF) is both a globally occurring and a frequent phenomenon in the Earth’s lower atmosphere (e.g. Chu.Journal of Aerosol Science 159 (2022) 105878 et al, 2019; Kerminen et al, 2018; Kulmala et al, 2004)
What is missing is the exact connection between the molecular clusters and atmospheric NPF events, making it difficult to quantify the link between emissions of aerosol precursors and potential influences of atmospheric NPF on climate or human health
We were able to show that a) that the pseudo-steady state approximation is valid in the studied conditions and b) that the measured cluster concentrations in the 2–3 nm size range agree with the estimated ones typically within a factor of 2–10

Summary

Introduction

New particle formation (NPF) is both a globally occurring and a frequent phenomenon in the Earth’s lower atmosphere (e.g. Chu (http://creativecommons.org/licenses/by/4.0/).Journal of Aerosol Science 159 (2022) 105878 et al, 2019; Kerminen et al, 2018; Kulmala et al, 2004). As outlined by Kulmala et al (2014), atmospheric NPF is a multi-step process starting from molecular cluster formation and eventually leading to a growing aerosol particle population. We have accu mulated plenty of information on atmospheric NPF events in terms of their frequency of occurrence, and the associated particle formation and growth rates at sizes larger than 3 nm of the particle diameter (Chu et al, 2019; Kerminen et al, 2018). What is missing is the exact connection between the molecular clusters and atmospheric NPF events, making it difficult to quantify the link between emissions of aerosol precursors and potential influences of atmospheric NPF on climate or human health. A key factor towards building this connection is to understand the properties of 1.5–3 nm atmospheric clusters, including their concentration in different environments

Objectives

Results

Conclusion