A complete file description is available here . The following plots show time-series of several measures of UV irradiance. Most recent results are contrasted to historic data allowing to compare measurements of different years. With the exception of the UV Index, data shown here are obtained from observations recorded near local apparent noon at each site. Investigators are cautioned that use of these data will be subject to revision.
Gaps sometimes appear in the series.
These are caused by either communications or instrument problems, and data for such periods may be available later in the season. Data shown here are obtained from observations recorded near local apparent noon at each site. Hourly data are also available. Note that data from Palmer 1989, shown on previous updates, has been removed from this update due to instrument instability. It serves as a vehicle to raise public awareness about the potential detrimental effects on health from solar UV exposure and to alert people of the need to adopt protective measures.