Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network
| Autor: | H. Lonka, Kimmo Korhonen, Markku Kulmala, M. Bauer-Pfundstein, Kari E. J. Lehtinen, A. Poikonen, Mikko Kurri, Terhi K. Laurila, Mika Komppula, Edith Rodriguez, A. Hirsikko, Y. Viisanen, Timo Karppinen, Ari Laaksonen, Tuukka Petäjä, Dmitri Moisseev, J. Heinonen, Annika Nordbo, V. Aaltonen, Curtis R. Wood, Ewan O'Connor, E. Giannakaki, Eija Asmi, A. Pfüller, Heikki Lihavainen |
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| Rok vydání: | 2013 |
| Předmět: |
Atmospheric Science
Backscatter Meteorology 010504 meteorology & atmospheric sciences lcsh:TA715-787 lcsh:Earthwork. Foundations 010501 environmental sciences Snow Ceilometer 01 natural sciences Aerosol Trace gas law.invention lcsh:Environmental engineering Telescope Lidar law 13. Climate action ddc:550 Environmental science Ka band lcsh:TA170-171 Remote sensing 0105 earth and related environmental sciences |
| Zdroj: | Atmospheric Measurement Techniques, Vol 7, Iss 5, Pp 1351-1375 (2014) Atmospheric measurement techniques 7(5), 1351-1375 (2014). doi:10.5194/amt-7-1351-2014 Atmospheric Measurement Techniques |
| DOI: | 10.5194/amtd-6-7251-2013 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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