TEMIS -- UV index & UV dose based on GOME -- archive

UV index & UV dose based on GOME	UV radiation monitoring
Overview of the data product archive

Monthly averages versus 10-day averages
It is common practice to produce monthly averages of quantities that fluctuate from day to day, such as the UV index and the UV dose, in order to better understand the yearly variation. The following graph shows the erythemal UV index for 2002 for Rome, from day to day as well as the monthly average of these data.

Daily values of the erythemal UV index at Rome in 2002 and a monthly average over the data (1 unit equals 25 mW/m2).

From this graph it is clear that the monthly average UV index changes considerably between some months, notably in Spring and Autumn. To even better represent the yearly variation, averages over periods of 10 days may be more suited, as the following graph shows. This is why the UV index and UV dose archive contains both monthly and 10-day averages (except for the UV dose computed on the basis of the ISCCP cloud cover climatology, as that climatology is monthly-averaged).

Daily values of the erythemal UV index at Rome in 2002 and a 10-day average over the data (1 unit equals 25 mW/m2).

A separate page shows as an example world maps of differences between monthly UV index averages and differences between 10-day averages.