The Puijo measurement station in Kuopio joined the SMEAR network in 2009 as the SMEAR IV station. 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 and meteorological parameters. The characteristic features at SMEAR IV are the elevated location in a semi-urban area and the site being frequently in cloud. The station is operated by the Atmospheric Measurements group at the Atmospheric Research Centre of Eastern Finland of Finnish Meteorological Institute (FMI) and the Aerosol Physics group at the Department of Applied Physics of the Kuopio campus of University of Eastern Finland (UEF).

The measurement station is on the top of a Puijo Tower (62° 54' 34" N, 27° 39' 19" E), which is a 75m high building on the Puijo hill (elevation 150m), approximately 2 km northwest of the city center of Kuopio. The measurements are carried out at the height of 306 m a.s.l. and 224 m above the surrounding lake level. More information about SMEAR IV Puijo station and measurements.

Reference for SMEAR IV Puijo measurements: Leskinen, A., Portin, H., Komppula, M., Miettinen, P., Arola, A., Lihavainen, H., Hatakka, J., Laaksonen, A. & Lehtinen, K. E. J. 2009: Overview of the research activities and results at Puijo semi-urban measurement station. Boreal Env. Res. 14: 576–590 (pdf).

Interstitial (int) and total (tot) inlets

Sample air for the instruments is drawn through two parallel sampling lines: interstitial (int) and total (tot) inlets:

  • interstitial inlet (int) is equipped with an impactor with a 10-μm cut-off size followed by a cyclone with a 1.0-μm cut-off size (2.5 μm before 20 November 2009)
  • total air inlet (total) with heated sampling lines and snow-hood to dry the cloud droplets (cut-off size 40 μm when the wind speed is below 20 m/s)

This two-inlet setup enables simultaneous interstitial and total air (interstitial + cloud drop residual) measurements when the tower is covered by clouds.

Data available from the SMEAR IV (tables):


  • Cloud Droplet Probe (CDP) data

PUI_dmps_int PUI_dmps_tot

  • Particle sizer distributions measured with Differential Mobility Particle Sizer (DMPS)
  • two different inlets: interstitial (_int) and total (_tot) inlet
  • interstitial inlet remove cloud droplets (by impactor and cyclone) whereas total inlet contains both interstitial particles and cloud drop residuals


  •  Particle diameters for DMPS diameter channels/bins (both int and tot)
  •  Size distributions have been measured using different diameters ranges at different periods:
  1. from 10 to 500 nm, 30 channels, 2.6.2006 - 31.3.2007
  2. from 7 to 800 nm, 40 channels, 1.4.2007 - 31.1.2012
  3. from 3 to 800 nm, 40 channels, from 1.2.2012

PUI_maap_int PUI_maap_tot

  • Multiangle Absorption Photometer (MAAP), a instrument that measures black carbon and aerosol light absorption properties).
  • two different inlets: interstitial (_int) and total (_tot) inlet

PUI_neph_int PUI_neph_tot

  •  nephelometer data, light-scattering coefficients of aerosol
  •  two different inlets: interstitial (_int) and total (_tot) inlet


  • weather data (temperature, RH, wind speed and directions, etc.)