UV index and UV dose: surface albedo correction
|Main data product description page|
Surface albedo correctionThe amount of UV radiation received by someone at the Earth's surface is affected by the local surface albedo: the larger the surface albedo, the more UV radiation. For this reason the UV index and UV dose calculation applies the following correction function of surface albedo (
A), which takes multiple reflections between the surface and the overlying atmosphere into account:f(A) = ( 1 — 0.25·0.09 ) / ( 1 — 0.25·A )Since the UV index parametrisation is empirally based on UV data collected at De Bilt and Paramaribo, the
Aat these (urban) sites -- with a 12-month average value of
0.09-- is used as a normalisation factor for the calculation of
The data for
Aat each 0.25°×0.25° UV grid cell are taken at 340 nm from the monthly GOME-2A surface albedo climatology -- available through this page -- interpolated linearly in time to daily values, associating the monthly average values with the 15th of the month.
The surface albedo climatology comes with an error estimate, which is also time interpolated and subsequently propagated to the UV index and UV dose error estimates.
Daily albedo data
Select a day in the menu on the left to access the file with surface albedo used for that date in the TEMIS UV processing through the following link:
The data is given days in a leap year. For non-leap years tbe albedo of 16 Feb. through 14 March will be marginally different due to the time interpolation.
last modified: 10 March 2018
data product contact: Jos van Geffen & Michiel van Weele & Roanld van der A
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