Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-1140
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
23 Dec 2016
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Metrics to quantify the importance of mixing state for CCN activity
Joseph Ching1, Jerome Fast1, Matthew West2, and Nicole Riemer3 1Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
2Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801, USA
3Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, 105 S Gregory St., Urbana, IL 61801, USA
Abstract. It is commonly assumed that models are more prone to errors in predicted CCN concentrations when the aerosol populations are externally mixed. However, it has been difficult to rigorously investigate this assumption because appropriate metrics for mixing state were lacking and metrics needed to quantify the error in CCN concentrations due to mixing state effects were unavailable. In this work we use the mixing state index (χ) proposed by Riemer and West (Atmos. Chem. Phys., 13, 11423–11439, 2013) to quantify the degree of external and internal mixing of aerosol populations. We combine this metric with particle-resolved model simulations to quantify error in CCN predictions when mixing state information is neglected, exploring a range of scenarios that cover different conditions of aerosol aging. We show that mixing state information does indeed become unimportant for more internally-mixed populations, more precisely for populations with χ larger than 60 %. For more externally-mixed populations (χ below 20 %) the relationship of χ and the error in CCN predictions is not unique, and ranges from lower than −40 % to about 150 %, depending on the underlying aerosol population and the environmental supersaturation. We explain the reasons for this behavior with detailed process analyses.

Citation: Ching, J., Fast, J., West, M., and Riemer, N.: Metrics to quantify the importance of mixing state for CCN activity, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1140, in review, 2016.
Joseph Ching et al.
Joseph Ching et al.
Joseph Ching et al.

Viewed

Total article views: 246 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
191 42 13 246 5 12

Views and downloads (calculated since 23 Dec 2016)

Cumulative views and downloads (calculated since 23 Dec 2016)

Viewed (geographical distribution)

Total article views: 246 (including HTML, PDF, and XML)

Thereof 246 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 26 Mar 2017
Publications Copernicus
Download
Share