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Observations of fluorescent aerosol-cloud interactions in the free troposphere at the High-Altitude Research Station Jungfraujoch

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Crawford I., Lloyd G., Herrmann E., Hoyle C. R., Bower K. N., Connolly P. J., Flynn M. J., Kaye P. H., Choularton T. W., Gallagher M. W.,
Project Beitrag an den Unterhalt und Betrieb der Hochalpinen Forschungsstationen Jungfraujoch und Gornergrat, 2015-2017
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Original article (peer-reviewed)

Journal Atmospheric Chemistry and Physics
Volume (Issue) 16
Page(s) 2273 - 2284
Title of proceedings Atmospheric Chemistry and Physics
DOI 10.5194/acp-16-2273-2016

Open Access

URL http://dx.doi.org/10.5194/acp-16-2273-2016
Type of Open Access Publisher (Gold Open Access)

Abstract

The fluorescent nature of aerosol at a high-altitude Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultraviolet - light-induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this highaltitude site and also investigating possible influences of UVfluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor increase in the fluorescent aerosol fraction during in-cloud cases compared to out-of-cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80% of 10 mu m particles being fluorescent. Whilst the fluorescent particles were in the minority (N-Fl / N-All = 0.27 +/- 0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosols were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1 +/- 0.4 L-1. Given the low concentration of this cluster and the typically low ice-active fraction of studied PBAP (e.g. pseudomonas syringae), we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.
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