The statistical methodology of extreme precipitation events: an authorial proposal for analysis of daily rainfall episodes

Abstract

Maximum precipitation accumulators, also called extreme rainfall events in the scientific literature, generally have energy with the potential to trigger major disasters, especially when they occur in locations inhabited by populations in vulnerable situations. Such events, characterized by having large deviations from the moderate climatic state, are usually categorized from the use of statistical methodologies, although there are other possibilities of analysis that consider, for example, their magnitude from the material and human damage they cause. Although rare episodes are considered, scientists linked to the Intergovernmental Panel on Climate Change (IPCC) say that extreme events are increasingly recurrent and intense, which represents a warning in the context of climate crisis/emergency observed today. In order to evaluate, objectively and operationally, the occurrence and intensity of daily rainfall episodes considered extreme, we propose here a new authorial statistical methodology that allows categorizing daily episodes of precipitation for a given locality, considering all the accumulated in long historical series. To validate its use and evaluate its effectiveness, records obtained from the website of the National Institute of Meteorology (INMET) were considered, selecting seven Brazilian cities representing the national territory and with different precipitation behaviors. The promising preliminary results allowed a comparative analysis between localities on the recurrence and intensity of extreme daily events, operationalizing the concept and employing different classes/intensity levels, always considering the reality of each locality regarding the behavior of rain.