A Comprehensive Methodology to Assess Tropospheric Fade Affecting Earth–Space Communication Systems

ATMospheric simulator for PROPagation applications (ATM PROP), a comprehensive methodology to assess tropospheric effects affecting high-frequency earth-space communication systems, is presented. The model takes advantage of physically based approaches aimed at synthesizing high-resolution (1 km × 1 km horizontal, 100-m vertical) 3-D fields of rain, clouds, and water vapor (dimension: 200 km × 200 km horizontal, 20-km vertical), which are all merged so as to maintain their mutual correlation. This, in turn, enables a more realistic combination of the attenuation due to single constituents, if compared to the statistical approach currently recommended by the ITU-R. The accuracy of ATM PROP in predicting tropospheric effects on earth-space systems is initially validated against the large propagation data set collected at the experimental station of Spino d'Adda, Italy, during the ITALSAT propagation campaign. The preliminary results obtained suggest that ATM PROP can be used to predict, with a reasonable level of complexity and limited coarse-resolution Numerical Weather Prediction-derived inputs, the tropospheric fade affecting complex communication systems (e.g., site diversity schemes), especially those involving low elevation links (e.g., low earth orbit or geostationary orbit at high latitude), for which the spatial distribution of the relevant tropospheric constituents needs to be taken in due account.