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| Titel |
Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network |
| VerfasserIn |
A. Hirsikko, E. J. O'Connor, M. Komppula, K. Korhonen, A. Pfüller, E. Giannakaki, C. R. Wood, M. Bauer-Pfundstein, A. Poikonen, T. Karppinen, H. Lonka, M. Kurri, J. Heinonen, D. Moisseev, E. Asmi, V. Aaltonen, A. Nordbo, E. Rodríguez, H. Lihavainen, A. Laaksonen, K. E. J. Lehtinen, T. Laurila, T. Petäjä, M. Kulmala  , Y. Viisanen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 5 ; Nr. 7, no. 5 (2014-05-19), S.1351-1375 |
| Datensatznummer |
250115761
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| Publikation (Nr.) |
 copernicus.org/amt-7-1351-2014.pdf |
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| Zusammenfassung |
| The Finnish Meteorological Institute, in collaboration with the University
of Helsinki, has established a new ground-based remote-sensing network in
Finland. The network consists of five topographically, ecologically and
climatically different sites distributed from southern to northern Finland.
The main goal of the network is to monitor air pollution and boundary layer
properties in near real time, with a Doppler lidar and ceilometer at each
site. In addition to these operational tasks, two sites are members of the
Aerosols, Clouds and Trace gases Research InfraStructure Network (ACTRIS); a
Ka band cloud radar at Sodankylä will provide cloud retrievals
within CloudNet, and a multi-wavelength Raman lidar, PollyXT
(POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and
microphysical aerosol properties through EARLINET (the European Aerosol
Research Lidar Network). Three C-band weather radars are located in the
Helsinki metropolitan area and are deployed for operational and research
applications. We performed two inter-comparison campaigns to investigate the
Doppler lidar performance, compare the backscatter signal and wind profiles,
and to optimize the lidar sensitivity through adjusting the telescope focus
length and data-integration time to ensure sufficient signal-to-noise ratio (SNR)
in low-aerosol-content environments. In terms of statistical
characterization, the wind-profile comparison showed good agreement between
different lidars. Initially, there was a discrepancy in the SNR and
attenuated backscatter coefficient profiles which arose from an incorrectly
reported telescope focus setting from one instrument, together with the need
to calibrate. After diagnosing the true telescope focus length, calculating
a new attenuated backscatter coefficient profile with the new telescope
function and taking into account calibration, the resulting attenuated
backscatter profiles all showed good agreement with each other. It was
thought that harsh Finnish winters could pose problems, but, due to the
built-in heating systems, low ambient temperatures had no, or only a minor,
impact on the lidar operation – including scanning-head motion. However,
accumulation of snow and ice on the lens has been observed, which can lead
to the formation of a water/ice layer thus attenuating the signal
inconsistently. Thus, care must be taken to ensure continuous snow removal. |
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