Spectral UV and visible irradiance measurements in the Barents Sea and Svalbard

Abstract

Using a single monochromator, spectral measurements of solar irradiances of the UV and visible spectral ranges have been carried out during the midnight sun period in Arctic regions. Diurnal intensity variations are similar throughout the whole spectral region. Spectral ratios of the regions are obtained, and strong diurnal variations of the spectral ratios caused by the ozone layer are documented. The UVB region is mostly affected by the ozone layer. With UVB as the numerator in the spectral ratios the maxima of the spectral ratios occur at midday, because then the optical path of the UVB through the ozone layer is shortest. With UVA as the numerator hardly any diurnal variation between this range and visible blue occurs, mainly because of the small influence of ozone attenuation in these wavelength ranges. The influence of weather has much less influence on the spectral ratios than on the irradiances.