Numerical weather prediction models for the estimate of clear-sky attenuation level in Alphasat beacon measurement

With the move of satellite systems towards Ka and Q/V bands, the Alphasat TDP5 Aldo Paraboni scientific experiment aims to characterize atmospheric attenuation in those bands. However, during the retrieval of the attenuation from the measured beacon signal, the clear-sky contribution to attenuation is lost. Microwave radiometers give the clear sky absolute reference level, but these are costly and not always available. This paper proposes Numerical Weather Prediction models as an alternative source of clear-sky attenuation. Three months of beacon and radiometric data from Spino d'Adda Alphasat receiving station are used as benchmark for the validation of the method. A preliminary conclusion is that gaseous attenuation is well predicted, but cloud attenuation is underestimated.