Extreme Rainfall Events in the state of Rio Grande do Sul, Brazil, Between 2004 and 2013. Part 1: Events Definition and Statistics

Abstract This article evaluated the extreme rainfall events occurred between 2004 and 2013 in the state of Rio Grande do Sul, Brazil. The extreme events were separated into two groups: daily and persistent events, which were identified with meteorological stations from INMET. For both classes of events, any trend of increase or decrease in the number of events was detected. The daily extreme events have higher frequency in spring and summer, while the persistent extreme events have higher frequency in winter. Spatialisation of rainfall, of persistent extreme events, showed that the east half of state of Rio Grande do Sul has a higher frequency of persistent rainfall events with larger rainfall quantities. In a second article, the atmospheric patterns will be investigated, as well as their relationships with the observed rainfall spatialisation, obtained in this first article.