Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Assessment of ultraviolet spectroradiometers

The performances of various ultraviolet spectroradiometers were assessed and compared as a series of intercomparison campaigns (1991-1995). Recommendations for further improvements were made.

Five international intercomparison campaigns for solar UV spectroradiometers have been held in Europe, 4 in the field and 1 in the laboratory. The number of participating instruments increased from 6 in 1991 to 13 in 1995. Vast improvements in instrument performance, calibration procedures, intercomparison techniques and understanding of the requirements for good UV measurements have been made. The results of the intercomparisons have been published. A variety of special instruments are used for solar UV measurements, ranging from the full commercial design (Brewer spectrophotometer) to the modified commercial unit (Bentham (UK) or Optronic (US) instrument based) to custom built designs. The instrument secifications for spectral solar UV measurements are stringent. If these are met, and the equipment demonstrates good stability, then agreement between different instruments depends upon calibration and operational procedures. Advances in these procedures have reduced discrepancies between a subset of instruments to small identifiable errors (below 3%) due to differences in absolute calibration standards available from the different National Standards Laboratories, and to nonideal cosine responses of the input optics. These two problems must be addressed if furthur advances are to be made.


Ann WEBB, (Lecturer)
Tel.: +44-161-2003917
Fax: +44-161-2003941