Retrieval of the ultraviolet effective snow albedo during 1998 winter campaign in the French Alps.
A measurement campaign was carried out in February 1998 at Briançon Station, French Alps (44.9 degrees N, 6.65 degrees E, 1,310 m above sea level) in order to determine the UV effective snow albedo that was retrieved for both erythemal and UV-A irradiances from measurements and modeling enhancement factors. The results are presented for 15 cloudless days with very variable snow cover and a small snowfall in the middle of the campaign. Erythemal irradiance enhancement due to the surface albedo was found to decrease from approximately +15% to +5% with a jump to +22% after the snowfall, whereas UV-A irradiance enhancement decreased from 7% to 5% and increased to 15% after the snowfall. Thesevalues fit to effective surface albedos of 0.4, 0.1, and 0.5 for erythemal, and to effective albedos of 0.25, 0.1, and 0.4 for UV-A irradiances, respectively. An unexpected difference between the effective albedos retrieved in the two wavelength regions can be explained by the difference of the environment contribution.
Smolskaia
Irina
I
Equipe Interactions entre Rayonnement Solaire et Atmosphere, Université Joseph Fourier, 17 quai Claude Bernard, 38000, Grenoble, France.
Masserot
Dominique
D
Lenoble
Jacqueline
J
Brogniez
Colette
C
de la Casinière
Alain
A