Markku Kulmala, Pertti Hari and colleagues in APFE Group started the SMEAR II station in 1995, with an extensive range of measurement interests. The station is located in the Hyytiälä Forestry Field Station of the University of Helsinki, in Juupajoki in southern Finland and is situated in a 62-year-old (in 2024) Scots pine stand. The main idea of SMEAR type infrastructures is continuous, comprehensive measurements of fluxes, storages and concentrations in the land ecosystem–atmosphere continuum and the site has full carbon, water and nitrogen budgets. The forest measurements are operated continuously since 1996, and include e.g. leaf, stand and ecosystem scale measurements of greenhouse gases, volatile organic compounds, pollutants (e.g. O3, SO2, NOx) and aerosols, in addition to full suite of meteorological measurements. Soil and soil-water measurements are performed on two water catchment areas. The biogeochemical cycles and vegetation–soil–atmosphere interactions are studied both experimentally and with long-term observations. The site is class 1 ICOS ecosystem and atmospheric station and an ACTRIS site. It also belongs to eLTER and AnaEE RIs. It has several operation units to reach into and above the stand canopy: a 128 m high tower for atmospheric and flux measurements, 18 m towers for flux and tree physiology measurements and 35 m walk-up tower for aerosol measurements. Ecosystem and atmosphere measurements also exist nearby in two open oligotrophic fen sites and a humic lake with a forested catchment.

Most of the measured data can be retrieved from: https://smear.avaa.csc.fi/”

photos by J.Aalto and M. Loponen.