Analysis of the Rain Anomaly Index and Precipitation Trend for Pluviometric Stations in Central Amazonia

Abstract

Climate change is a response to the dynamics of the Earth system to intrinsic or extrinsic factors to the planet. Important consequences of this climate change are the occurrence of droughts or an increase in the intensity of rainfall in various regions of the globe, which can reduce or increase the availability of water in the system. For the Amazon, the drought severity scenario may worsen, as suggested by climate models. The purpose of this work is to analyze the rain anomaly and the precipitation trend for the period from 1994 to 2017 in seven pluviometric stations located in Central Amazonia and relate them to the events El Niño and La Niña. For this, the Rain Anomaly Index (RAI) and the Mann-Kendall non-parametric trend assessment test were used. The results suggest that only extreme El Niño, such as those in 1997 and 2015, showed a decrease in precipitation, while La Niña in 1999 was the one that showed the greatest increases, from the RAI. Regarding the Mann-Kendall trend test, only at station C it showed a tendency to increase in precipitation, showing the need for larger precipitation time series for more concise analyzes.