A network of five stations measuring the solar UV-radiation has been operated for about five years. Data are presented as plotted time-series of monthly and yearly values for the sites. A general climatology can be deduced from these data. Daily and hourly maximum values are shown for each month as indicators of the potential extreme exposure levets. The !arge amma! variation at high latitudes is easily seen in the data set. This illustrates the importance of rhe solar elevation on the leve! of the UV-irradiance. Influence of cloud variation and of larger changes in ozone is also detectable. A few examples of the daily variation also show the strong solar elevation dependence of the UV-irradiance.
The quantity and unit of the UV-radiation in this presentation is CIE-weightecl irradiance expressed as MED (minimum erythemal dose), where one MED equals 210 Jnf 2• The values have been re- computed to refer to the international intercomparison of broad-band meters in Helsinki in 1995. In the following named WMO-STUK 1995 scale.
As will be seen there are many sources of error and detailed studies are prevented by the !arge uncertainty connected with these data, Due to the short period of the record and the low accuracy no attempt to study trends is done.