**1. Introduction**

Since precipitation is one of the most important climate variables, as its variations directly affect numerous human activities, the knowledge about this variable's spatial and temporal variability is crucial to subsidize the decision-making and actions planning to minimize impacts caused by extreme precipitation events.

The North East of Brazil (NEB) is a region with a difficult climatic characterization as a result of geographic factors associated with different atmospheric systems. Then, there are different factors that fluctuate the precipitation regime of the NEB on a wide time and space scale [1–4].

A large part of the climate studies about analyses of precipitation that focus the NEB report mainly the water deficit. Trying to understand the complex social functions of these climatic characteristics is very important since they cause economic losses in addition to deaths. In contrast, heavy rainfall is also reported, which, together with water deficits, are the main types of adverse natural phenomena from the NEB, so those cause significant impacts that can be catastrophes.

Since intense rainfall events have become increasingly more common and strong, according to projections made by the Intergovernmental Panel Climate Change (IPCC) [5],

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**Citation:** de Araújo, P.A.A.; Silva, C.M.S.e.; Rodrigues, D.T.; Valentim, A.M. Analysis of Extreme Rainfall Events on a Sub-Daily Scale in Northeast. *Environ. Sci. Proc.* **2023**, *25*, 97. https://doi.org/10.3390/ ECWS-7-14299

Academic Editor: Athanasios Loukas

Published: 3 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

there is vast scientific literature on extreme indices on a daily scale around the world, including in the NEB [6]. However, initiatives to analyze extreme rainfall on a sub-daily scale are still incipient, as well as the hourly analysis, mainly due to the lack of meteorological data with hourly or minute sampling. That said, the objective of the present study was to characterize the spatial and temporal distribution of the Subdaily Scale Intense Precipitation Events (EPIES) over the NEB from hourly data collected in the period between 2009 and 2018, analyzing the seasonality of the number of events for each location and the influence of interannual variability on the occurrence of EPIES.

### **2. Materials and Methods**

### *2.1. Study Area*

The NEB is located latitudinally between 1◦ S and 18◦ S and longitudinally between 48◦ W and 34◦ W. It comprises a territorial extension of 1,558,000 km2, according to the Brazilian Institute of Geography and Statistics [7], comprising 9 states.

### *2.2. Data Collection*

The dataset refers to precipitation observations from 119 automatic surface meteorological stations that are distributed in the NEB and are operated by the Brazilian National Institute of Meteorology (INMET). Data were collected hourly for the period between 1 January 2009 and 31 December 2018.

To organize the dataset and apply the methodology, Microsoft Excel software was used to calculate the results. The exploratory analysis of the heavy precipitation indices of each meteorological station was conducted using the R statistical computational system, realized through a box-plot cartogram, which is a graphic technique that shows the behavior of the data in space.
