A large population of radar-measured ground rain cells is used to devise and assess a rain cell model for use in some of the future telecommunication applications. The model is based on cells of exponential profile (which is shown to reproduce best the point rain rate CDF); both rotational and biaxial symmetries are considered for the horizontal cross sections. Furthermore, the proposed model contains analytical expressions for the joint probability densities of the parameters which define the cell, i.e., peak rain intensity, cell size and axial ratio. Finally, an algorithm is given for adapting the model to the characteristics of any given site: this algorithm requires as input the local cumulative distribution of point rainfall and provides the spatial number densities (i.e., the average number of cells per square kilometer and per unit range of the parameters) which this distribution would produce. The model offers the possibility of predicting the statistics of many propagation parameters (such as attenuation or interference by rain scattering) which are determined by the rain cell characteristics and their frequency of occurrence. assumption is made that the same types of precipi-during 1980 near Milan, Italy. tation occur in different locations' what varies is the The model is based on a distribution of cells each frequency of their occurrence. Yet propagation pre-one characterized by an exponential profile of the diction models become a powerful tool in predicting rain rate (in the following referred to as "model statistics of the quantities of interest only if the model cells"). parameters can be derived from local meteorological The statistical properties of the population of data [Rogers, !976]. "model cells" are presented and discussed together with the procedure for linking the parameters of the •Dipartimento di Elettronica, Centro di Studio per le Telecom-model to the meteorological data. rnunicazioni Spaziali CNR Politeenico di Milano, Milano, Italy. A rain cell is defined as any connected region of aFondazione Ugo Bordoni, Rome, Italy. space composed of points where the rain rate exceeds aCentro di Studio per le Telecomunicazioni Spaziali CNR Poli-a given intensity threshold. tecnico di Milano, Milano, Italy. The "model cell" is identified by forcing some of Copyright 1987 by the American Geophysical Union. its integral parameters to correspond with those of Paper number 6S0709. the observed cell. 0048-6604/87/006s-0709508.00 Two models of cell are dealt with' a monoaxial 395 in the range 6-150 mm/h is given by (19). Konrad, T. G., Statistical models of summer rainshowers derived rom fine-scale radar observations, J. Appl Meteorol., 17(2), 171-4. No(R•t ), the number density of R u, in Figure 199,1978. 8, is given in the form of a cumulative distribution Lane, S. O., and W. L. Stutzman, Spatial rain rate distribution normalized to the total number of cells exceeding 5 modeling for earth-spaoe link propagation calculations, paper 404 CAPSONI ET AL.: RAIN CELL MODELING FOR PROPAGATION APPLICATIONS pr...