Technical Note : Using DEG-CPCs at upper tropospheric temperatures

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Wimmer , D , Lehtipalo , K , Nieminen , T , Duplissy , J , Ehrhart , S , Almeida , J , Rondo , L , Franchin , A , Kreissl , F , Bianchi , F , Manninen , H E , Kulmala , M , Curtius , J & Peta¨ja¨ , T 2015 , ' Technical Note : Using DEG-CPCs at upper tropospheric temperatures ' , Atmospheric Chemistry and Physics , vol. 15 , no. 13 , pp. 7547-7555 . https://doi.org/10.5194/acp-15-7547-2015 , https://doi.org/10.5194/acp-15-7547-2015

Title: Technical Note : Using DEG-CPCs at upper tropospheric temperatures
Author: Wimmer, D.; Lehtipalo, K.; Nieminen, T.; Duplissy, J.; Ehrhart, S.; Almeida, J.; Rondo, L.; Franchin, A.; Kreissl, F.; Bianchi, F.; Manninen, H.E.; Kulmala, M.; Curtius, J.; Peta¨ja¨, T.
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Public Health
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Social and Cultural Anthropology
Date: 2015
Language: eng
Number of pages: 9
Belongs to series: Atmospheric Chemistry and Physics
ISSN: 1680-7316
URI: http://hdl.handle.net/10138/161741
Abstract: Over the last few years, several condensation particle counters (CPCs) capable of measuring in the sub-3 nm size range have been developed. Here we study the performance of CPCs based on diethylene glycol (DEG) at different temperatures during Cosmics Leaving OUtdoor Droplets (CLOUD) measurements at CERN. The data shown here are the first set of verification measurements for sub-3 nm CPCs under upper tropospheric temperatures using atmospherically relevant aerosol particles. To put the results in perspective we calibrated the DEG-CPC at room temperature, resulting in a cut-off diameter of 1.4 nm. All diameters refer to mobility equivalent diameters in this paper. At upper tropospheric temperatures ranging from 246.15 K to 207.15 K, we found cut-off sizes relative to a particle size magnifier in the range of 2.5 to 2.8 nm. Due to low number concentration after size classification, the cut-off diameters have a high uncertainty (+/- 0.3 nm) associated with them. Operating two laminar flow DEG-CPCs with different cut-off sizes together with other aerosol instruments, we looked at the growth rates of aerosol population in the CLOUD chamber for particles smaller than 10 nm at different temperatures. A more consistent picture emerged when we normalized the growth rates to a fixed gas-phase sulfuric acid concentration. All of the instruments detected larger growth rates at lower temperatures, and the observed growth rates decreased as a function of temperature, showing a similar trend for all instruments. The theoretical calculations had a similar but much smaller temperature dependency.
Subject: ATMOSPHERIC AEROSOL NUCLEATION
CONDENSATION PARTICLE COUNTER
SULFURIC-ACID
SIZE DISTRIBUTIONS
ORGANIC-COMPOUNDS
1 NM
GROWTH
ION
NUCLEI
SPECTROMETER
114 Physical sciences
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