Análise de Índices de Extremos Climáticos no Nordeste e Amazônia Brasileira para o Período entre 1980 a 2013

Abstract

In Brazil, climate extreme events in the Amazon (AMZ) and Northeast (NEB) regions, such as heavy rainfall (floods and flash floods) and severe drought, alternate both in space and time. Floods, flash floods and droughts affect water quality and access which may impact public health through the proliferation of diseases, in addition to social and economic aspects. Thus, the objective of this study is to analyze trends in air temperature and rainfall climate extreme indices in the AMZ and the NEB. Meteorological data used in this study were from a joint project between the University of Texas (USA) and the Federal University of Espirito Santo (Brazil), made available on the website: https://utexas.box.com/Xavier-etal-IJOC-DATA and arranged in a 0.25° × 0.25° grid, for the period from 01 January 1980 to 31 October. 11 extreme air temperature indices and 10 extreme rainfall indices obtained from Climdex were used. Results showed possible local climate change in certain areas of the AMZ and the NEB, with the most important changes occurring in the temperature indices. It was observed that 48 mesoregions indicate an increase for the TXx index (maximum monthly maximum daily temperature), followed by the index TX90p (warm days), with 47 mesoregions, TNx (monthly maximum daily minimum temperature) and reduction for TX10p (cold days) with 42 mesoregions. Regarding rainfall indices in the AMZ and the NEB, it is noted that there have been changes in 20 or more mesoregions, especially in the R20mm (annual count of days when rainfall ≥ 20 mm), CDD (dry spell), R95p (wet days) and PRECPTOT (annual total precipitation on wet days) with positivi trend and RX5day (Monthly maximum consecutive 5-day precipitation) indices with positivi trend. Results also showed that from 21 indices selected according to the characteristics of the AMZ and the NEB, the mesoregion with the best evidence of climate change is the Outback of Sergipe with the occurrence of 20 statistically significant indices, followed by the South of Roraima with 16 indexes. However, there is a conjunction of factors such as deforestation, inefficient land use, among others, that should be taken into consideration and may be impacting the local climate of the studied regions.