Cloud-induced effects on monthly averaged scintillation amplitude along millimeter-wave slant paths

A physical-statistical analysis of cloud-induced effects on millimeter-wave amplitude scintillation along Earth-satellite slant paths is presented. Using numerical simulations derived from a cloud radiative model, a dual-channel nonlinear retrieval algorithm is set up to estimate simultaneously cloud columnar water vapor and liquid water contents from measured ground-based brightness temperatures. The latter are related in cloudy conditions to surface meteorological variables and columnar water vapor and liquid water contents. ITALSAT ground-station data consisting of time series of beacon scintillation at 18.7, 39.6, and 49.5 GHz, surface meteorological data and radiometric observations at 13.0, 23.8, and 31.6 GHz, are used for an experimental analysis of cloud-induced scintillation by selecting a period of six years from 1994 to 1999. The results show a significant correlation between amplitude scintillation variances and cloud columnar contents on a monthly basis (i.e., averaged on-time intervals of one month). Considerations about possible impact of this analysis on the development of scintillation prediction models are finally illustrated.