Climatology and significant trends in maximum, minimum and average air temperatures in Alagoas, Northeast Brazil

Abstract

Abstract The increase in air temperature can generate several environmental and socioeconomic impacts, so the main objective of this study was to characterize the monthly and annual profiles of maximum, minimum and average air temperatures and to identify whether there are significant trends in the time series of each, for the state of Alagoas, Brazil. For this, monthly data on maximum and minimum air temperatures (1980 to 2013) were used for 98 of the 102 municipalities in Alagoas. With the data in hand, the average air temperature was calculated and cluster analysis was applied to determine homogeneous sub-regions of the average air temperature. Trend analyzes were verified using nonparametric Mann-Kendall (sign of trend), Sen (magnitude of trend) and Pettitt (beginning of trend) tests. Analysis of variance (ANOVA) was used to verify differences between the decennial averages air temperatures. The statistical significance adopted was 5%. The results showed that the state of Alagoas has four sub-regions with homogeneous characteristics according to average air temperature. Sub-region 4 (S4), located in the Sertão (scrubland region) of Alagoas, had the highest average, maximum and minimum air temperatures, monthly and annually. Annually, significantly increasing trends were observed at 5% in the four sub-regions, with emphasis on S4, with increases above 1.0°C/décade in average, maximum and minimum temperatures. It is noteworthy that throughout the state of Alagoas, a significant trend of increase in the average air temperature was identified during the 34 years analyzed, highlighting the possible impacts of climate change.