The goal of this project is to find the relationships between the UV solar spectral irradiances sampled at ground level in different cloudy situations. This information will be useful for a double target: to a better tuning of the UV Green model outputs and to evaluate the effects of the solar UV radiation on biological target. A second target is to have information about the cloud effect on computing the Umkehr model output (vertical Ozone profiles). This goal will be carried out installing in Ny-Ålesund a spectrophotometer Brewer to sample the UV irradiance synchronous with an automatic photo-camera taking pictures of sky. An analytical study of the two kinds of data allows finding the relationships searched.