Measurement stations in Kuopio
Experimental research for the Atmospheric Research Centre of Eastern Finland is carried out on three measurement stations: Puijo, Savilahti, and Vehmasmäki.
Puijo
At Puijo the idea is to study the interactions of aerosol particles and clouds, especially the activation of aerosol particles into cloud droplets. The instrumentation covers measurement of aerosol dynamics, cloud droplet properties, optical measurements, trace gases, greenhouse gases, and meteorological parameters. The characteristic features are the elevated location (306 m above sea level, 224 m above surrounding lake level, on top of a 75 m tall observation tower standing on a 150 m high hill) in a semi-urban area (2 km northwest of the centre of Kuopio) and the site being frequently (approximately 15 % of the time) in cloud. The station is jointly operated by the Atmospheric Observations group and the Aerosol Physics group at the Department of Applied Physics of the Kuopio campus of University of Eastern Finland (UEF), and is part of ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure).
The measurements cover aerosol size distribution and number concentration, light extinction (scattering and absorption) by aerosol particles, cloud droplet size distribution, trace gas concentration, greenhouse gas concentration, and several meteorological parameters. The aerosol size distribution and optical properties are measured through two inlets: an interstitial, which removes cloud droplets and particles larger than 1.3 µm in diameter, and a total air inlet, which allows aerosol particles and cloud droplets smaller than 40 µm in diameter to enter the sampling line. In the total air inlet the cloud droplets are dried and both the remaining residual and interstitial particles are measured. The difference between the total aerosol and interstitial aerosol gives then the fraction of activated particles as a function of particle size.
The Puijo measurement station is also part of the SMEAR (Station for Measuring Ecosystem-Atmosphere Relations) network since 2009 and has provided ICOS (Integrated Carbon Observation System) compliant data since October 2020 (preceded by a demo experiment phase that started 2011).
Savilahti
The Savilahti site is at the Kuopio campus area of the UEF, approximately 2 km southwest from Puijo and approximately 2 km west from the center of Kuopio. The site is at the height of 87 m above sea level and 5 m above the surrounding lake level. At Savilahti, FMI has an automated weather station measuring several meteorological parameters, including the cloud base height measured with a ceilometer, and also instruments for measuring solar radiation. Observations of the weather and solar radiation in Savilahti can be accessed at data download site. In addition to the weather measurements, aerosol optical properties are measured by using a sun photometer that belongs to the AERONET (AErosol RObotic NETwork) network maintained by the US National Aeronautics and Space Association (NASA). Measurements of the direct solar radiation provide information to retrieve the columnar aerosol optical depth, while the sky radiance measurements can be inverted to produce aerosol optical properties such as size distribution, single scattering albedo, phase functions, and the complex index of refraction. Furthermore, the global solar radiation is measured with a pyranometer that belongs to the SolRad-Net (Solar Radiation Network) network implemented as a companion to AERONET and also maintained by NASA.
Vehmasmäki
Vehmasmäki is located in a forested rural area approximately 20 km south of Kuopio city centre. Established in 2012 next to a 318 m telecommunications mast, the station supports research on aerosols, clouds, pollen and atmospheric icing.
The station’s main remote-sensing instrument is a PollyXT multiwavelength Raman lidar, which is also part of EARLINET (the European Aerosol Research Lidar Network) and ACTRIS (Aerosol, Clouds and Trace Gases Research Infrastructure). The lidar measures vertical profiles of atmospheric particles at three wavelengths, 355, 532 and 1064 nm. It also provides information on light extinction at two wavelengths, particle depolarization at all three wavelengths and water vapor micing ratios. This PollyXT lidar is also equipped with fluorescence-detection capability. Together, the spectral depolarization and fluorescence measurements allow detailed observations of aerosol and pollen layers from approximately 100 m above ground level to altitudes of several tens of kilometres, with a vertical resolution of 7.5 m.
Pollen research is an important and growing activity at Vehmasmäki. Traditional pollen monitoring is carried out using a Burkard volumetric pollen sampler, which collects airborne pollen for subsequent identification and counting. These observations are complemented by automatic and real-time instruments, including Poleno and Plair Rapid-E+.
Additional remote sensing measurements of aerosols, clouds and winds are provided by a HALO StreamLine Doppler lidar, a Metek MIRA-35 cloud radar and a Vaisala CL61 & CL51 ceilometers. Station includes also a Cimel CE318-T Sun/Sky/Lunar Multispectral Photometer connected to AERONET (Aerosol Robotic Network). At ground level, in-situ particle mass and size distributions, light-scattering and absorption coefficients, and black carbon concentrations are measured. Present-weather conditions, including visibility, are also continuously monitored.
The 318 m mast provides a unique facility for studying atmospheric icing, which can cause operational problems in sectors such as aviation and renewable-energy production. Icing measurements are conducted at heights of 115 and 272 m. The mast includes additional pollen (115 & 272 m), 3D winds (115 m) and visibility (272 m) sensors. Supporting measurements of temperature and relative-humidity are conducted at seven levels, 2, 66, 115, 168, 215, 272 and 300 m, as well as wind-speed and wind-direction measurements at 26, 115, 215 and 272 m.
