Articles | Volume 7, issue 5
Atmos. Meas. Tech., 7, 1351–1375, 2014
Atmos. Meas. Tech., 7, 1351–1375, 2014

Research article 19 May 2014

Research article | 19 May 2014

Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

A. Hirsikko1,2, E. J. O'Connor1,3, M. Komppula4, K. Korhonen4, A. Pfüller4, E. Giannakaki4, C. R. Wood1, M. Bauer-Pfundstein5, A. Poikonen1, T. Karppinen6, H. Lonka1, M. Kurri1, J. Heinonen1, D. Moisseev7, E. Asmi1, V. Aaltonen1, A. Nordbo7, E. Rodriguez1, H. Lihavainen1, A. Laaksonen1, K. E. J. Lehtinen4,8, T. Laurila1, T. Petäjä9, M. Kulmala9, and Y. Viisanen1 A. Hirsikko et al.
  • 1Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
  • 2Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung: Troposphäre (IEK-8), Jülich, Germany
  • 3Meteorology Department, University of Reading, Reading, UK
  • 4Finnish Meteorological Institute, P.O. Box 1627, 70211 Kuopio, Finland
  • 5Meteorologische Messtechnik GmbH (METEK), Elmshorn, Germany
  • 6Finnish Meteorological Institute, Tähteläntie 62, 99600 Sodankylä, Finland
  • 7Dept. of Physics, University of Helsinki, P.O. Box 48, 00014 Helsinki, Finland
  • 8University of Eastern Finland, Dept. Applied Physics, P.O. Box 1627, 70211 Kuopio, Finland
  • 9Dept. of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland

Abstract. 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.