SPATIAL AND TEMPORAL VARIABILITY OF PRECIPITATION IN THE NORTHERN AMAZON: A CHRONOLOGICAL ANALYSIS

Resumo

The Amazon region has a fundamental role in the global hydrological balance because it is one of the regions that have high rainfall and evapotranspiration levels due to its vast tropical rain forest. For this reason, spatial and temporal analyses of rainfall are essential in order to evaluate the impacts of climate change. The objective of this research was to analyze the spatial and temporal patterns of twelve years (2000-2011) of rainfall data from ten sites in the Venezuelan Amazon. The spatial and temporal structures of interannual rainfall variability were analyzed using Principal Components Analysis with a correlation matrix and grouping techniques. The Mann-Kendall non-parametric test was used to determine if annual rainfall trends at each site can be identified using a time series that includes a seasonal component. When the 10 sites were separated into groups of average annual rainfall and for average rainfall between years, three homogeneous groups of rainfall were distinguished. With respect to monthly rainfall at each site, monthly rainfall defined the homogeneous rainfall groups. These results show that in this region of the Amazon a unimodal pattern of precipitation predominates at the different sites, with a long period of rainfall and a period with less rainfall between December and March. This pattern is explained by the Intertropical Convergence Zone which during these months is shifted to more southern latitudes, thus modifying the rainfall dynamics in the Amazon.