Climatology and significant trends in air temperature in Alagoas, Northeast Brazil

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 analyses 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 average 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 Sertao (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/decade in average, maximum, and minimum temperatures. These results may help decision makers who need knowledge about the behavior and trends of air temperature (average, maximum, and minimum).

Automated summary

The main objective of this study was to characterize the monthly and annual profiles of maximum, minimum, and average air temperatures and to identify significant trends in the time series. The results showed increasing trends in average, maximum, and minimum temperatures in all sub-regions, with the highest increases observed in the scrubland region.