Long-term variations of UV-B doses at three stations in northern Europe

• Published in: Journal of Geophysical Research Vol. 105; no. D16; p. 20
• Main Authors: Kaurola, Jussi, Taalas, Petteri, Koskela, Tapani, Borkowski, Janusz, Josefsson, Weine
• Format: Journal Article
• Language: English
• Published: 27-08-2000
• ISSN: 0148-0227

The long-term variation of UV radiation at three stations located in northern Europe (Belsk, Norrkoping, and Jokioinen) is studied using data from (1) ground-based observations, (2) surface UV doses determined using TOMS satellite measurements, and (3) reconstructed UV doses using observations of global radiation, total ozone, and radiative transfer modeling. For each station the estimates of daily UV doses from various sources are intercompared, and a trend analysis is performed to reveal long-term changes in the UV radiation. Data sets, which start in the late 1970s or early 1980s, show a general positive trend in annual doses of UV radiation. Some of these upward trends are statistically significant. For Belsk the increases are in the range of 5-15 percent per decade during spring and summer. The largest increases, about 20 percent/decade, have been observed in Norrkoping during spring. At Jokioinen there has been a slight upward trend in UV throughout the year. The analysis of reconstructed Belsk data from 1966 onward shows that the positive trend since late 1970s was preceeded by a negative trend. The reason for such changes is probably not only related to the changes in the total ozone but also to changes in aerosol content and cloudiness. The agreement of the UV series based on different data sources is good. The different trend estimates were in very close agreement with each other. However, there were often differences in absolute values, which is probably due to problems in calibration and limitations of the models. (Author)