Chemical and physical influences on aerosol activation in liquid clouds. A study based on observations from the Jungfraujoch, Switzerland
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Authors
Hoyle, Christopher R.
Webster, Clare S.
Rieder, Harald E.
Nenes, Athanasios
Hammer, Emanuel
Herrmann, Erik
Bukowiecki, Nicolas
Author (Corporation)
Publication date
2016
Typ of student thesis
Course of study
Collections
Type
01A - Journal article
Editors
Editor (Corporation)
Supervisor
Parent work
Atmospheric Chemistry and Physics
Special issue
DOI of the original publication
Link
Series
Series number
Volume
16
Issue / Number
6
Pages / Duration
4043-4061
Patent number
Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
Edition
Version
Programming language
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Practice partner / Client
Abstract
A simple statistical model to predict the number of aerosols which activate to form cloud droplets in warm clouds has been established, based on regression analysis of data from four summertime Cloud and Aerosol Characterisation Experiments (CLACE) at the high-altitude site Jungfraujoch (JFJ). It is shown that 79 % of the observed variance in droplet numbers can be represented by a model accounting only for the number of potential cloud condensation nuclei (defined as number of particles larger than 80 nm in diameter), while the mean errors in the model representation may be reduced by the addition of further explanatory variables, such as the mixing ratios of O3, CO, and the height of the measurements above cloud base. The statistical model has a similar ability to represent the observed droplet numbers in each of the individual years, as well as for the two predominant local wind directions at the JFJ (northwest and southeast). Given the central European location of the JFJ, with air masses in summer being representative of the free troposphere with regular boundary layer in-mixing via convection, we expect that this statistical model is generally applicable to warm clouds under conditions where droplet formation is aerosol limited (i.e. at relatively high updraught velocities and/or relatively low aerosol number concentrations). A comparison between the statistical model and an established microphysical parametrization shows good agreement between the two and supports the conclusion that cloud droplet formation at the JFJ is predominantly controlled by the number concentration of aerosol particles.
Keywords
Subject (DDC)
500 - Naturwissenschaften
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ISBN
ISSN
1680-7324
1680-7316
1680-7316
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
Citation
HOYLE, Christopher R., Clare S. WEBSTER, Harald E. RIEDER, Athanasios NENES, Emanuel HAMMER, Erik HERRMANN, Martin GYSEL, Nicolas BUKOWIECKI, Ernest WEINGARTNER, Martin STEINBACHER und Urs BALTENSPERGER, 2016. Chemical and physical influences on aerosol activation in liquid clouds. A study based on observations from the Jungfraujoch, Switzerland. Atmospheric Chemistry and Physics. 2016. Bd. 16, Nr. 6, S. 4043–4061. DOI 10.5194/acp-16-4043-2016. Verfügbar unter: https://doi.org/10.26041/fhnw-7709