Phenomenological validation of a regional rainfall frequency analysis

The interpretation of the experimental evidence of the presence of a double component in the distribution of rainfall annual maxima (RAM) observed along the Tyrrhenian coast of Italy is discussed here. Using a simple model for rainfall storm generation the effect of the presence or absence of the European blocking condition on the generation of the double component in the RAM is investigated. The model is calibrated on the essential meteorological characteristics of the Mediterranean storms provided both by remote sensing and high resolution raingauge data. It allows to give a physical explanation for the variability of the parameters distribution with time observation interval. The maxima extracted from the model generated rainfall time series show statistical properties very similar to those obtained by sample data. In particular the model derived rainfall frequency curves and intensity duration frequency curves show a good agreement with the observed ones.