A combined Pòlya process and mixture distribution approach to rainfall modelling

摘要

A new probabilistic interpretation of at site rainfallsequences is introduced for the development of a stochastic model of rain.The model, is divided into two sub models; the first one describing thetotal number of rainfall spells within a window of time is described bya Pòlya process in order to reproduce better the variable probability ofoccurrence of rainfall during storm events (due to the presence of differentnumbers of rainfall cells); the second sub model, conditional on the firstone, describes the total quantity of rainfall in the time window, givena number of rainfall spells. The probabilistic rainfall model, which hasshown interesting properties in reproducing the probability distributionof observed data at time scales ranging from one hour to twenty-four hours,may be the basis for a number of applications which include the developmentof a conditional stochastic generator of rain, within the frame of real-timeflood forecasting, and the derivation of a probabilistic distribution ofrainfall extremes at the various time scales.