Measurement of relative humidity dependent light scattering of aerosols
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Authors
Fierz-Schmidhauser, Rahel
Zieger, Paul
Wehrle, Günther
Jefferson, Anne
Ogren, John A.
Baltensperger, Urs
Author (Corporation)
Publication date
21.01.2010
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Type
01A - Journal article
Editors
Editor (Corporation)
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Parent work
Atmospheric Measurement Techniques
Special issue
DOI of the original publication
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Series
Series number
Volume
3
Issue / Number
1
Pages / Duration
39-50
Patent number
Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
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Abstract
Relative humidity (RH) influences the water content of aerosol particles and therefore has an important impact on the particles' ability to scatter visible light. The RH dependence of the particle light scattering coefficient (σsp is therefore an important measure for climate forcing calculations. We built a humidification system for a nephelometer which allows the measurement of σsp at a defined RH in the range of 40–90%. This RH conditioner consists of a humidifier followed by a dryer, which enables us to measure the hysteresis behavior of deliquescent aerosol particles. In this paper we present the set-up of a new humidified nephelometer, a detailed characterization with well defined laboratory generated aerosols, and a first application in the field by comparing our instrument to another humidified nephelometer. Monodisperse ammonium sulfate and sodium chloride particles were measured at four different dry particle sizes. Agreement between measurement and prediction based on Mie theory was found for both σsp and f(RH)=σsp(RH)/σsp(dry) within the range of uncertainty. The two humidified nephelometers measuring at a rural site in the Black Forest (Germany) often detected different f(RH), probably caused by the aerosol hysteresis behavior: when the aerosol was metastable, therefore was scattering more light, only one instrument detected the higher f(RH).
Keywords
Subject (DDC)
550 - Geowissenschaften
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ISBN
ISSN
1867-8548
1867-1381
1867-1381
Language
English
Created during FHNW affiliation
No
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
Citation
FIERZ-SCHMIDHAUSER, Rahel, Paul ZIEGER, Günther WEHRLE, Anne JEFFERSON, John A. OGREN, Urs BALTENSPERGER und Ernest WEINGARTNER, 2010. Measurement of relative humidity dependent light scattering of aerosols. Atmospheric Measurement Techniques. 21 Januar 2010. Bd. 3, Nr. 1, S. 39–50. DOI 10.5194/amt-3-39-2010. Verfügbar unter: https://doi.org/10.26041/fhnw-9676