Observations of fluorescent aerosol–cloud interactions in the free troposphere at the High-Altitude Research Station Jungfraujoch
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 meteorolo...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/2273/2016/acp-16-2273-2016.pdf |
| Summary: | 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 high-altitude site and also investigating possible influences of UV–fluorescent
particle types on cloud–aerosol processes.
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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 μm particles
being fluorescent. Whilst the fluorescent particles were in the minority
(<i>N</i><sub>Fl</sub>∕<i>N</i><sub>All</sub> = 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<sup>−1</sup>. Given the low concentration of this cluster and
the typically low ice-active fraction of studied PBAP
(e.g. <i>pseudomonas syringae</i>), we suggest that the contribution to the
observed ice crystal concentration at this location is not significant during
the wintertime. |
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| ISSN: | 1680-7316 1680-7324 |