Select Yearly UV Index graphs

The graphs of measured UV Index are based on ground-based measurements available from the World Ozone and Ultraviolet Radiation Data Centre.

The graphs of estimated UV Index are based on measurements of global solar radiation, humidity and snow, available from the National Climate Data Archive (sites in Canada), and the National Solar Radiation Data Base (sites in USA), along with data on the ozone layer available from the World Ozone and Ultraviolet Radiation Data Centre.

In the graphs of all observations, every observation is represented by one pixel, with the colour showing the UV index.

In the graphs of daily maximum UV index, the highest index measured each day is shown. The Indices are indicated by red dots. Estimates of UV Index for clear sky no-snow conditions and “normal” pre-1980 total ozone values are shown by a blue line. Estimates of UV Index for clear sky conditions and the day's total ozone values are shown by a magenta line (if available and not covered). If the day's ozone is equal to normal the magenta line will cover the blue line.