Variability of ground-level ultraviolet: Model and measurement

A method to describe the observed yearly variability of ground-level UV has been developed and validated. The method uses UV transfer model calculations and measured ozone values, by satellite or ground based stations, in combination with an empirical cloud correction based on widely available global solar radiation measurements. Good agreement is found between the modelled and measured yearly sums of UV radiation monitored at the RIVM site for the past five years. The agreement is on an absolute scale. Using ozone and broadband measurements, a trend analysis of the actual yearly UV load becomes feasible. Initial results show an increase in the yearly erythemal UV dose at ground-level of 10% rising from 41 J.cm(-2) for the period 1979-1981 to 45 J.cm(-2) for the period 1996-1998.