A comparison between radiative transfer calculation and pyranometer data gathered at Observatoire de Haute Provence

The energy received on the ground from the sun is calculated using the Tropospheric Ultraviolet Visible (TUV) model of Madronich and Flocke (Handbook of Environmental Chemistry, Boule, P., (Ed.), Springer-Verlag, Heildelberg; pp. 1-26). Additions are made for running the model up to the infrared domain. Moreover, modifications in the algorithms describing several physical processes experienced by the solar radiations and models of the atmosphere properties are replaced by available local data in the area where the calculation is needed. For that, specific aerosols distribution, spectral absorption cross section of water vapour, local albedo season dependent and a recent extraterrestrial solar spectrum from UV to IR obtained from space measurements, are used. At Observatoire de Haute Provence (44°N, 6°E), a set of instruments provide us with information necessary to run the TUV model. Furthermore, the energy including the scattered and direct solar irradiance is measured by pyranometers in two wavelength ranges. To validate the additions made to the model, comparisons in clear sky conditions between the observations and the model output are made. The additions led to increase the accuracy of the model predictions to about 4%. Furthermore, this study shows that pyranometers characterization have to be improved by taking into account the contribution of the scattered light at large solar zenith angle.