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| Titel |
Spatial variation of aerosol optical properties around the high-alpine site Jungfraujoch (3580 m a.s.l.) |
| VerfasserIn |
P. Zieger, E. Kienast-Sjögren, M. Starace, J. Bismarck, N. Bukowiecki, U. Baltensperger, F. G. Wienhold, T. Peter, T. Ruhtz, M. Collaud Coen, L. Vuilleumier, O. Maier, E. Emili, C. Popp, E. Weingärtner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 15 ; Nr. 12, no. 15 (2012-08-08), S.7231-7249 |
| Datensatznummer |
250011380
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| Publikation (Nr.) |
 copernicus.org/acp-12-7231-2012.pdf |
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| Zusammenfassung |
| This paper presents results of the extensive field campaign CLACE 2010 (Cloud
and Aerosol Characterization Experiment) performed in summer 2010 at the
Jungfraujoch (JFJ) and the Kleine Scheidegg (KLS) in the Swiss Alps. The main
goal of this campaign was to investigate the vertical variability of aerosol
optical properties around the JFJ and to show the consistency of the
different employed measurement techniques considering explicitly the effects
of relative humidity (RH) on the aerosol light scattering. Various aerosol
optical and microphysical parameters were recorded using in-situ and remote
sensing techniques. In-situ measurements of aerosol size distribution, light
scattering, light absorption and scattering enhancement due to water uptake
were performed at the JFJ at 3580 m a.s.l.. A unique set-up allowed remote
sensing measurements of aerosol columnar and vertical properties from the KLS
located about 1500 m below and within the line of sight to the JFJ
(horizontal distance of approx. 4.5 km). In addition, two satellite
retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI)
and the Moderate Resolution Imaging Spectroradiometer (MODIS) as well as back
trajectory analyses were added to the comparison to account for a wider
geographical context. All in-situ and remote sensing measurements were in
clear correspondence. The ambient extinction coefficient measured in situ at
the JFJ agreed well with the KLS-based LIDAR (Light Detection and Ranging)
retrieval at the altitude-level of the JFJ under plausible assumptions on the
LIDAR ratio. However, we can show that the quality of this comparison is
affected by orographic effects due to the exposed location of the JFJ on a
saddle between two mountains and next to a large glacier. The local RH around
the JFJ was often higher than in the optical path of the LIDAR measurement,
especially when the wind originated from the south via the glacier, leading
to orographic clouds which remained lower than the LIDAR beam. Furthermore,
the dominance of long-range transported Saharan dust was observed in all
measurements for several days, however only for a shorter time period in the
in-situ measurements due to the vertical structure of the dust plume. The
optical properties of the aerosol column retrieved from SEVIRI and MODIS
showed the same magnitude and a similar temporal evolution as the
measurements at the KLS and the JFJ. Remaining differences are attributed to
the complex terrain and simplifications in the aerosol retrieval scheme in
general. |
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