Modeling high-resolution 3-D cloud fields for earth-space communication systems

A methodology to synthesize 3-D spatially correlated cloud fields from Numerical Weather Prediction (NWP) products is presented. The target area is 200 km × 200 km and the horizontal spatial resolution is 1 km × 1 km. The field synthesis relies on the stochastic approach proposed by Bell, and the main model's parameters are extracted from high-resolution cloud fields observed by the MODIS sensor. The model's inputs are the fractional cloud cover and the average integrated cloud liquid water content provided by an NWP dataset (the ERA40 reanalysis in this study). Also, the vertical profile of clouds is modelled, based on the analysis of data collected by the Cloud Profiling Radar onboard the CloudSat satellite. Tests on the model performance indicate that first-order (complementary cumulative distribution function) and second-order (spatial distribution) statistics of the integrated cloud liquid water content are reproduced with good accuracy in several sites in Europe. The proposed model is one of the main blocks of a simulator of weather disturbances affecting radio-wave propagation, primarily intended to support the design and performance assessment of Earth space communication systems (EHF range or optical wavelengths) but also of possible interest for all of the applications involving radiative transfer in the atmosphere.