- 1CERN, European Organisation for Nuclear Research, Geneva, Switzerland
- 2Faculty of Physics, University of Vienna, Vienna, Austria
- 3Faculty of Sciences of the University of Lisbon, Lisbon, Portugal
- 4Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- 5INAR, Faculty of Science, University of Helsinki, Helsinki, Finland
- 6Institute of Physics, Faculty of Science and Technology, University of Tartu, Tartu, Estonia
- 7Institute of Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
- 8Ionicon Analytik Ges.m.b.H., Innsbruck, Austria
- 9Paul Scherrer Institute, Villigen PSI, Switzerland
- *A full list of authors appears at the end of the abstract
New particle formation (NPF) contributes to about half of all cloud condensation nuclei worldwide (Gordon et al. 2017) and plays a critical role in understanding anthropogenic climate change (IPCC, 2021). A keymechanism driving atmospheric NPF is acid-base nucleation, primarily involving anthropogenic sulfuric acid and ammonia (Kirkby, 2023). Nonetheless, oxygenated organic molecules (OOM), produced from oxidation of terpenes like alpha-pinene (Kirkby et al. 2016) or – in the upper troposphere – isoprene (Shen et al. 2024), can drive rapid particle nucleation in the complete absence of sulfuric acid, a process known as pure biogenic nucleation.
Shen et al. (2024) found that that the addition of trace amounts of sulfuric acid to isoprene-driven NPF enhanced the nucleation rates up to 100-fold. However, so far, a synergistic effect of sulfuric acid with alpha-pinene OOM (AP-OOM) has not been reported.
This study focuses on measurements from the CERN CLOUD chamber, examining NPF from alpha-pinene in the presence of trace sulfuric acid concentrations ranging from 104 to 106 cm−3, levels that are commonlyfound in pristine regions. Experiments were conducted at -10°C and +5°C, typical of the cool boundary layer of boreal forest regions, and in the absence of any base vapors such as ammonia or amines.
Gas-phase concentrations were monitored using various CI-Time-Of-Flight mass spectrometers (Nitrate-CIMS, Fusion PTR, STOF PTR-MS, FIGAERO), while naturally charged nucleating clusters were analyzed using an APi-TOF. Aerosol particle distributions were characterized with an array of particle measurement instruments (scanning PSM, CPC, NAIS, nSMPS, lSMPS, DMA-Train). Nucleation and growth rates were determined under varying concentrations of alpha-pinene OOMs and sulfuric acid.
This study presents nucleation and growth rates from AP-OOM in the presence of trace sulfuric acid and compares the rates with those from pure AP-OOM and pure sulfuric acid, respectively.
Gordon, H. et al. (2017) Causes and importance of new particle formation in the present-day and preindustrial atmospheres. J. Geophys. Res. Atmos. 122, 8739-8760.
IPCC (2021) Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
Kirkby, J. et al. (2016) Ion-induced nucleation of pure biogenic particles. Nature 533, 521-526.
Kirkby, J. et al. (2023) Atmospheric new particle formation from the CERN CLOUD experiment. Nature Geoscience 16, 948-957.
Shen, J. et al. (2024) "New particle formation from isoprene under upper-tropospheric conditions." Nature 636.8041, 115-123.
CLOUD Collaboration
How to cite: Sommer, E., Almeida, J., Simon, M., Caudillo-Plath, L., Yu, W., Junninen, H., Zheng, Z., Judmaier, B., Shen, J., Dada, L., and Kirkby, J. and the CLOUD Collaboration: New particle formation from alpha pinene and trace sulfuric acid in the CERN CLOUD chamber, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19500, https://doi.org/10.5194/egusphere-egu25-19500, 2025.