Use and accuracy of numerical weather predictions to support em wave propagation experiments

In order to keep up with the demand for new services, future satellite-to-ground communications will operate at higher frequencies, notably in the 20-50 GHz bands. Consequently, new challenges arise for system designers as the attenuation of the signal crossing the troposphere increases with frequency. Propagation experiments, such as the on-going Alphasat campaign, provide direct measurements of the attenuation. However, other data sources, such as collocated radiometers, are needed to recover the attenuation in nonrainy conditions. This paper uses the Weather Research and Forecasting (WRF) software and investigates Numerical Weather Prediction (NWP) models as an alternative source of nonrainy attenuation time series. Four months of measured Alphasat and radiometric signals collected at Spino d'Adda serve as the reference to assess the accuracy of NWP-derived attenuation. The best agreement between the NWP-derived and the radiometric nonrainy attenuations is achieved with the Tiedtke cumulus scheme. Considering the limits in accuracy inherent to the propagation and radiometric data, the resulting total attenuation statistics are acceptable. The results are expected to improve further with NWP simulation domains closer to the state of the art.