SPI-Based Drought Classification in Italy: Influence of Different Probability Distribution Functions

Drought is ranked second in type of natural phenomena associated with billion dollars weather disaster during the past years. It estimated that EU countries number people affected by drought was increased 20% over last decades. widely recognized Standardized Precipitation Index (SPI) can effectively provide characteristics time and space. The paper questions standard approach to estimate SPI based on Gamma probability distribution function, assessing fitting performance different biparametric laws monthly precipitation data. We series, for scale temporal aggregation, an unprecedented dataset consisting 332 rain gauge stations deployed across Italy observations recorded between 1951 2000. Results show Lognormal performs better than data at all scales, affecting from signals. However, events detected using original best approaches does not diverge consistently terms return period. This suggests its formulation be applied a reliable detection promoting mitigation strategies Italian peninsula.