Abstract
A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are reanalyzed in the present study with an advanced method. The results show that the NPF rates at 1.7nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at a larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 and 4.3nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range of sizes (up to ca. 30nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement for the high base-to-acid ratios (∼100) relevant for this study. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically controlled) NPF for the conditions during the CLOUD7 experiment (278K, 38% relative humidity, sulfuric acid concentration between 1 × 106 and 3 × 107cm-3, and dimethylamine mixing ratio of ∼ 40pptv, i.e., 1 × 109-3).
Original language | English |
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Pages (from-to) | 845-863 |
Journal | Atmospheric Chemistry and Physics |
Volume | 18 |
Issue number | 2 |
DOIs | |
Publication status | Published - 23 Jan 2018 |
MoE publication type | A1 Journal article-refereed |
Funding
Funding from the German Federal Ministry of Education and Research (grant no. 01LK1222A) and the Marie Curie Initial Training Network “CLOUD-TRAIN” (grant no. 316662) is gratefully acknowledged. Peter H. McMurry’s and Chenxi Li’s contributions to this work were supported by the US Department of Energy’s Atmospheric System Research program and Office of Science, Office of Biological and Environmental Research, under grant number DE-SC0011780. Federico Bianchi thanks the Swiss National Science Foundation (grant no. P2EZP2_168787). Richard C. Flagan acknowledges funding from the NSF grants 1439551 and 1602086. Matti P. Rissanen appreciates funding from the Academy of Finland (project no. 299574). Katrianne Lehtipalo thanks the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 656994 (nano-CAVa).