Homogenization of the Belsk UV‐B series (1976–1997) and trend analysis

Abstract

An analysis of the ultraviolet radiation measurements taken at Belsk by Robertson‐Berger meter and Brewer spectrophotometer over the period 1976–1997 is performed. In the Robertson‐Berger data series, a mean level shift that can be attributed to change in calibration procedure was detected. In the examination of the series, a wavelet analysis was used. To determine the magnitude of the shift, a relationship between UV radiation and total ozone for a clear sky was applied. The results showed that for the Robertson‐Berger data, over the period 1984–1992, the correction factor of 1.14 should be applied. The trend in the whole observational period was 6.1±2.9% per decade. In the estimation of the trend uncertainty, the autocorrelation in the noise and shift of the level in the data was taken into account. The UV‐B trend depends mainly on the trend of ozone, and the response of UV‐B to ozone changes is most evident for the variations of the ozone content at a large timescale.