Unfiltering of the Geostationary Earth Radiation Budget (GERB) data. Part I: Shortwave radiation - Clerbaux,N; Dewitte,S; Bertrand,C; Caprion,D; De,Paepe B; Gonzalez,L; Ipe,A; Russell,J; Brindley,H (Journal of Atmospheric and Oceanic Technology, 2008)