Climatology and trends of surface UV radiation

An improved understanding of the global ultraviolet (UV) climate has recently become of great interest. A number of stations are now making regular measurements of spectrally-resolved UV-B irradiance. Despite the lack of long-term records, it is possible to describe many of the short-term characteristics, dependencies and climatology of surface UV-B irradiance. This article describes the current state of UV-B measurements, and a climatology of surface UV-B irradiance with particular focus on Canada. The dependence of UV irradiance on ozone and other climate variables is discussed in detail, with reference to observations. In addition, comparison of radiative transfer models with recent measurements indicates that it is possible to infer surface UV-B irradiance from older records of total ozone and ancillary measurements (spectrally-integrated irradiance, aerosol optical depth and surface albedo) permitting the derivation of longer-term trends.