A comparison of dosimeters used for solar ultraviolet radiometry

Radiometric measurements of terrestrial sunlight using three different types of broad-band dosimeters were compared with equivalent integrated quantities obtained from simultaneous spectroradiometric measurements. Measurements were made at Durham, UK (55 degrees N) during one day in mid-summer and one day in the autumn. By this means it was possible to encompass a wide range of ultraviolet irradiances. There was close agreement between UV-A irradiance measured using a broad-band radiometer and determined spectroradiometrically over the whole range of irradiances when allowance was made for the spectral sensitivity of the UV-A radiometer. The agreement between erythemally-effective irradiance determined spectroradiometrically and the response of a Robertson-Berger meter showed some non-linearity due to the mismatch between the erythema action spectrum and spectral response of the sensor. There was a similar disparity in agreement between erythemally-effective dose determined spectroradiometrically and the response of polysulphone film for similar reasons. Nevertheless it is concluded that if these latter two dosimeters are calibrated using sunlight, or a solar simulator, as the source, they can yield data which are sufficiently reliable for many applications.