Regional precipitation index: Method analysis and application over Greece

The current work focuses on the development of a regional precipitation index (RPI) to rank precipitation events in Greece, with the goal of identifying the most severe weather events in terms of their potential to cause socioeconomic impacts. The study is motivated by the increasing occurrence of extreme weather events and accompanying hydrogeological phenomena worldwide, which have caused significant infrastructure damage and loss of life. The analysis is based on the exploitation of the ERA-Land high-resolution rainfall dataset, covering the period from 1991 to 2020, while it considers both the area and the population affected by each rainfall event. The study provides a categorization of the ranked storms based on the percentiles of all non-zero RPI values and highlights the socioeconomic impacts of the most severe weather events. The findings suggest that the developed RPI can be a useful tool for early warning systems and risk management strategies, particularly for emergency preparedness and response. The resulting ranking procedure has been applied operationally by the METEO unit of the National Observatory of Athens since fall 2021.