Análise temporal dos eventos extremos de precipitação em São Gabriel da Cachoeira/AM e Monte Alegre (1993 a 2021), Amazônia brasileira

Abstract

The occurrence of extreme precipitation events is an increasingly common reality in the Brazilian Amazon, an area of great global climate importance, causing several negative impacts as a result of the complexity of a set of factors, amidst a scenario driven by climate change. The objective of this work was to analyze the occurrence of extreme precipitation events in the municipalities of São Gabriel da Cachoeira - AM and Monte Alegre - PA, in the period 1993- 2021. For this purpose, we used the collection of secondary information from government agencies. The meteorological data were extracted from the Meteorological Database for Teaching and Research (BDMEP), made available by the National Institute of Meteorology – INMET, the deforestation and fire outbreak data were obtained through BDQueimadas and Prodes (INPE) respectively, the data of occurrence of ENSO phenomena were derived from NASA, NOAA and CEPTEC (INPE), population data came from IBGE and on the vehicle fleet came from SENATRAN. To analyze the data in the research on the occurrences of precipitation extremes in the study areas, total daily precipitation records that exceeded or were equal to 30 mm, 50 mm and 70 mm were adopted. From the analyzes carried out, it was verified that São Gabriel reached a total number of events, in the three criteria, of 30% more compared to the Monte Alegre station, however Monte Alegre presented the day with the highest rainfall rate with 175.4 mm in 17 /11/2019, in contrast São Gabriel only reached 150 mm on 02/12/1993. It was observed that events in both seasons had greater occurrences in the rainy period, which generally corresponds to the first half of the year, also including December. During these years, only events greater than or equal to 50 mm showed similar patterns in both seasons. In São Gabriel, there was a small increase between 2002 and 2016, while in Monte Alegre there was a slight increase from 2003 to 2012. It was noted in both seasons that only events ≥ 30 mm followed a pattern similar to the rainfall behavior. Furthermore, when considering the possible factors responsible for these occurrences, the strong influence of the atmospheric phenomena ZCIT, ZCAS, Instability Line and the Continental Equatorial Mass stands out initially, with a temporal correlation between the period of greatest activity of these phenomena and the highest occurrence of precipitation extremes in both seasons. In addition to these phenomena, the La Niña atmospheric-oceanic system stands out and when carrying out a temporal comparison with the extreme precipitation rates, only 1999 and 2011 showed a possible relationship with extreme events at the same time in both seasons. Furthermore, other possible factors include the increase in global warming, population growth in the region studied from the mid-70s onwards, a strong increase in the number of vehicles, high rates of deforestation and fires in the respective states and in the Legal Amazon. . The study areas, as well as the corresponding region, express high vulnerability to these anomalous events, making it essential to delve deeper into these phenomena. Keywords: Extreme events; Precipitation; Climate changes; Amazon