ELDONET - Installation of a European Light Dosimeter Network

EU Program: ENVIRONMENT
Coordinator: Prof. D. P. Häder, Friedrich-Alexander Universät, Staudstr. 5, D-91058 Erlangen, Fed. Rep. Germany
Contract #: ENV4-CT96-0191, DG-XII
Status: Completed
Year: 1996
Duration: 48 months
EU contact person: Dr. C. Nolan, DG-XII
Partners: OikoTechnics Institute, Athens, Greece; Olof Bjorn, University of Lund, Lund, Sweden; K. Luning, Biologische Anstalt Helgoland, Hamburg, Germany; G. Colombetti, Institute of Biophysics, Pisa, Italy; M. Tevini, Universitat Karlsruhe, Karlsruhe, Germany; F. Lopez Figueroa, Univ. de Malaga, Balaga, Spain

Project objective

The aim is to build an accurate but low cost network for monitoring incident levels of PAR, UV-A, and UV-B on land as well as below sea surface. This network (European Light Dosimeter Network; "ELDONET") is intended to satisfy the specific interest of the scientific community in the study of the effects of solar radiation

Brief project description

While continuous monitoring of irradiances, fluences and temperatures is necessary for interpreting ecosystem responses to environmental changes, measurements up to now have in most cases been only temporary and unsystematic. To satisfy this need, a network has been installed of inexpensive but reliable light dosimeters at locations covering all latitudes and climatic regions in Europe, from Abisko in Northern Sweden to the Canary Islands. Solar radiation at the surface is monitored using sharp band sensors for PAR (photosynthetically active radiation), UV-A and UV-B. The signals from the sensors are amplified, digitized and stored in a dedicated computer; hourly and daily doses are calculated and stored. The instruments are frequently calibrated against a double monochromator spectroradiometer (Optronic 752). Specific care is taken to identify and correct for mechanical errors and deviation from the true values. Temperature is measured simultaneously and used in conjunction with the solar angle to correct the irradiance readings. In addition, a waterproof version of the instrument is used at several stations under water to determine irradiances and doses at the growing sites of the underwater flora and analyze the light penetration into the water column in representative European marine environments. Two stations are installed at a high altitude site specifically to determine the UV-B radiation that is significantly higher than at lowland sites. The instruments have been installed at all sites in Sweden, Germany, Italy, Spain and Greece, so that precise irradiances and doses of solar radiation have been obtained automatically over the past few years at representative sites in Europe.