Analysis of concentration and seasonality of precipitation in Recife - Pernambuco, Brazil
Silva da, Silva da, Rodrigo Cavalcanti, Passo do, Aguiar Dias, Albuquerque de, Ivana Tošić, Tatijana StošićThis study investigates the variability of precipitation distribution and rainfall seasonality regime in Recife-PE, Brazil, using the Precipitation concentration index (PCI) and Seasonality indices (SI). PCI was calculated on annual (PCI<sub>a</sub>), seasonal (PCI<sub>s</sub>), and supra-seasonal (PCI<sub>ss</sub>) scales for the period 1962-2020. Rainfall seasonality regime classification was performed using the individual seasonality index (SI<sub>i</sub>), the general seasonality index (SI), and the replicability index (RI). The PCI<sub>a</sub> time series revealed precipitation distribution ranging from moderate (79.66% of the years) and irregular, with mean value of PCI<sub>a</sub> ≈ 13.58. Seasonality analysis indicated a mean rainfall regime classified as rather seasonal with a short drier season (SI≈ 0.56), and a high degree of replicability (RI = 0.85), characterized by maximum rainfall concentrated in a few months and limited interannual variability in SI<sub>i</sub> values. Trend analysis using the Mann-Kendall test and Sen's slope estimator showed no significant trends in the time series of PCI and SI<sub>i</sub>, except for spring (PCI<sub>s</sub>), which exhibited a significant negative trend. A Spearman correlation analysis between SI<sub>i</sub> and PCI<sub>a</sub> yielded a strong positive correlation (ρ = 0.86), reinforcing the link between precipitation concentration and seasonality structure.