Ground-based ultraviolet radiation -measurements in Trondheim

摘要

A weatherproof spectroradiometer has been developed for spectral measurements of direct, global and radiance ultraviolet radiation. The core of the instrument is a Bentham D150 double monochromator with two input entrances with a swing away mirror. Two 4.0 m quarts fibres connect the optical input to the monochromator. Global irradiance was measured with an ideal cosine diffusor. Direct irradiance and radiance measurements were performed with a telescope having a field of view 1.5 °mounted on a weatherproof sun tracker. The whole system is operated by an integrated software, running the tracker and the spectroradiometer at the same time. Calibration of the direct unit and the global irradiance were done with a 1000 W FEL lamp. Langley calibration was found more difficult due to changing atmospheric conditions and difficulties having proper clear sky days. Radiance distribution was measured two days in May 2003, showing similar pattern as for other places with a low aerosol content.