Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.668 IF 5.668
  • IF 5-year value: 6.201 IF 5-year
    6.201
  • CiteScore value: 6.13 CiteScore
    6.13
  • SNIP value: 1.633 SNIP 1.633
  • IPP value: 5.91 IPP 5.91
  • SJR value: 2.938 SJR 2.938
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 174 Scimago H
    index 174
  • h5-index value: 87 h5-index 87
Volume 16, issue 16
Atmos. Chem. Phys., 16, 10385–10398, 2016
https://doi.org/10.5194/acp-16-10385-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 16, 10385–10398, 2016
https://doi.org/10.5194/acp-16-10385-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 17 Aug 2016

Research article | 17 Aug 2016

In-cloud measurements highlight the role of aerosol hygroscopicity in cloud droplet formation

Olli Väisänen1, Antti Ruuskanen2, Arttu Ylisirniö1, Pasi Miettinen1, Harri Portin3, Liqing Hao1, Ari Leskinen1,2, Mika Komppula2, Sami Romakkaniemi2, Kari E. J. Lehtinen1,2, and Annele Virtanen1 Olli Väisänen et al.
  • 1University of Eastern Finland, Department of Applied Physics, P.O. Box 1627, 70211 Kuopio, Finland
  • 2Finnish Meteorological Institute, P.O. Box 1627, 70211 Kuopio, Finland
  • 3Helsinki Region Environmental Services Authority, P.O. Box 100, 00066 HSY, Finland

Abstract. The relationship between aerosol hygroscopicity and cloud droplet activation was studied at the Puijo measurement station in Kuopio, Finland, during the autumn 2014. The hygroscopic growth of 80, 120 and 150  nm particles was measured at 90 % relative humidity with a hygroscopic tandem differential mobility analyzer. Typically, the growth factor (GF) distributions appeared bimodal with clearly distinguishable peaks around 1.0–1.1 and 1.4–1.6. However, the relative contribution of the two modes appeared highly variable reflecting the probable presence of fresh anthropogenic particle emissions. The hygroscopicity-dependent activation properties were estimated in a case study comprising four separate cloud events with varying characteristics. At 120 and 150 nm, the activation efficiencies within the low- and high-GF modes varied between 0–34 and 57–83 %, respectively, indicating that the less hygroscopic particles remained mostly non-activated, whereas the more hygroscopic mode was predominantly scavenged into cloud droplets. By modifying the measured GF distributions, it was estimated how the cloud droplet concentrations would change if all the particles belonged to the more hygroscopic group. According to κ-Köhler simulations, the cloud droplet concentrations increased up to 70 % when the possible feedback effects on effective peak supersaturation (between 0.16 and 0.29 %) were assumed negligible. This is an indirect but clear illustration of the sensitivity of cloud formation to aerosol chemical composition.

Publications Copernicus
Download
Short summary
In-cloud measurements of aerosol hygroscopicity and cloud droplet activation were conducted in Kuopio, Finland. According to the observations, the less hygroscopic accumulation mode particles were present in the non-activated aerosol, whereas the more hygroscopic particles were scavenged into cloud droplets. The results illustrate the sensitivity of cloud droplet formation to varying chemical composition and highlight the need for proper treatment of anthropogenic aerosols in CCN predictions.
In-cloud measurements of aerosol hygroscopicity and cloud droplet activation were conducted in...
Citation