References

ACP

Atmospheric Chemistry and Physics

ACP

Atmos. Chem. Phys.

1680-7324

Copernicus Publications

Göttingen, Germany

10.5194/acp-14-10547-2014

Ion – particle interactions during particle formation and growth at a coniferous forest site in central Europe

Gonser

S. G.

¹ Klein

https://orcid.org/0000-0002-3680-4735

¹ ⁴ Birmili

² Größ

² Kulmala

https://orcid.org/0000-0003-3464-7825

³ Manninen

H. E.

³ Wiedensohler

² Held

University of Bayreuth, BayCEER, Atmospheric Chemistry, 95448 Bayreuth, Germany

Leibniz Institute for Tropospheric Research, 04318 Leipzig, Germany

Department of Physics, University of Helsinki, 00014 Helsinki, Finland

now at: Gasphase and Aerosol Chemistry Group, Paul Scherrer Institute, 5232 Villigen, Switzerland

09 10 2014

14 19 10547 10563

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://acp.copernicus.org/articles/14/10547/2014/acp-14-10547-2014.html

The full text article is available as a PDF file from https://acp.copernicus.org/articles/14/10547/2014/acp-14-10547-2014.pdf

In this work, we examined the interaction of ions and neutral particles during atmospheric new particle formation (NPF) events. The analysis is based on simultaneous field measurements of atmospheric ions and total particles using a neutral cluster and air ion spectrometer (NAIS) across the diameter range 2–25 nm. The Waldstein research site is located in a spruce forest in NE Bavaria, Southern Germany, known for enhanced radon concentrations, presumably leading to elevated ionization rates. Our observations show that the occurrence of the ion nucleation mode preceded that of the total particle nucleation mode during all analyzed NPF events. The time difference between the appearance of 2 nm ions and 2 nm total particles was typically about 20 to 30 min. A cross correlation analysis showed a rapid decrease of the time difference between the ion and total modes during the growth process. Eventually, this time delay vanished when both ions and total particles did grow to larger diameters. Considering the growth rates of ions and total particles separately, total particles exhibited enhanced growth rates at diameters below 15 nm. This observation cannot be explained by condensation or coagulation, because these processes would act more efficiently on charged particles compared to neutral particles. To explain our observations, we propose a mechanism including recombination and attachment of continuously present cluster ions with the ion nucleation mode and the neutral nucleation mode, respectively.

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