Seasonal and diurnal variation of aerosol size distributions (10<D<750 nm) at a high‐alpine site (Jungfraujoch 3580 m asl)

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Authors
Nyeki, Stephan
Baltensperger, Urs
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Publication date
01.11.1999
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01A - Journal article
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Parent work
Journal of Geophysical Research: Atmospheres
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Volume
104
Issue / Number
D21
Pages / Duration
26809-26820
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Publisher / Publishing institution
Wiley
Place of publication / Event location
Hoboken
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Abstract
During an extended field campaign at a high-alpine site (Jungfraujoch; 3580 m asl, Switzerland) from March 1997 to May 1998, the particle number size distribution (diameter D = 18–750 nm) and number concentration N (D>10 nm) were measured on a continuous basis. The number size distribution was dominated by particles with D<100 nm, while most of the surface area was in the accumulation mode size range (0.1–1 μm). Average size distributions exhibited a distinct bimodal shape which is generated and maintained by cloud processes and is less distinct in the free troposphere. Fitted modal diameters and standard deviations σ of the Aitken (20–100 nm) and accumulation modes were surprisingly constant throughout the year (DAit = 43±3 nm; DAcc = 140±6 nm; σAit = 2.13±0.11; σAcc = 1.61±0.03). The relative number concentrations in both modes are responsible for the seasonally observed in the shape of the size distribution. The high seasonality of NAcc with summer and winter values of ∼260 and ∼40 cmˉ³, respectively, is mainly due to transport of planetary boundary layer air to the station. In contrast, new particle formation is responsible for the high concentrations of nucleation mode particles (D<20 nm) which exhibited a maximum during the winter months. The relatively low seasonality found for NAit (summer, winter values: ∼530, ∼310 cmˉ³) is due to gas-to-particle conversion as well as transport processes. An analysis showed that a significant fraction of nucleation mode particles were formed by photochemical reactions.
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550 - Geowissenschaften
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2169-897X
2169-8996
Language
English
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No
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Published
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Peer review of the complete publication
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Citation
WEINGARTNER, Ernest, Stephan NYEKI und Urs BALTENSPERGER, 1999. Seasonal and diurnal variation of aerosol size distributions (10<D<750 nm) at a high‐alpine site (Jungfraujoch 3580 m asl). Journal of Geophysical Research: Atmospheres. 1 November 1999. Bd. 104, Nr. D21, S. 26809–26820. DOI 10.1029/1999jd900170. Verfügbar unter: https://irf.fhnw.ch/handle/11654/46896