Assessment of spectral UV radiation at Marambio Base, Antarctic Peninsula

Abstract. This study aims to assess response of spectral UV radiation to different atmospheric and terrestrial factors, including solar zenith angle, ozone, cloud cover and albedo, in southern polar environment. For this purpose, 23260 individual spectra (300–363 nm), obtained by the B199 Mk-III Brewer spectrophotometer at Marambio Base, Antarctic Peninsula Region, over the period 2010–2020, were studied. A neural network model was developed to investigate the effects of the explanatory variables at individual wavelengths. SZA proved to be the most important parameter, followed by cloud cover, TOC, and surface albedo. The relative SZA effect is greatest at the shortest wavelengths, where a 1° decline in SZA results in a 6–18 % increase in UV irradiance (305 nm). Also TOC affects particularly the short wavelengths, while at 305 nm, a 10 DU decrease in TOC causes a 7–13 % increase in UV irradiance. In some seasons (e.g., 2011–2012, 2014–2015, 2018–2019), the large-scale ozone holes caused the UV irradiance at very short wavelengths peak in spring, whereas in other seasons (e.g., 2010–2011, 2012–2013), the maxima at all wavelengths were recorded in summer. The effect of cloud cover was strongest near the fully cloudy sky, and in summer months. Albedo affected the UV irradiance only weakly, its effect was strongest in early spring and late fall.