Joint effects of clouds and rain on Ka-band earth observation data downlink systems

This contribution addresses the evaluation of the simultaneous impact of clouds and rain on a Ka-band Data Downlink System involving a Low Earth Orbit (LEO) satellite for Earth Observation. To this aim, MultiEXCELL (Multi EXponential CELL) and SMOC (Stochastic MOdels of Clouds), two physically-based models recently developed to synthesize realistic rain and cloud fields as large as 10 km×200 km×200 km (height×width×depth), are employed. Taking advantage of their physical soundness, the two models are combined to derive the simultaneous attenuation due to rain and clouds on a Earth-LEO link operating at 26 GHz. Results obtained for Rome, NY, USA indicate that the data downlink system is affected by clouds for approximately 72% of the visibility time and that a 30-dB margin would be required to counteract the attenuation due to rain and clouds for 99.9% of the visibility time.