REGIONALIZATION OF PRECIPITATION ANOMALIES IN SOUTHEAST OF SOUTH AMERICA

Abstract

Southeast of South America presents complex climatic variability, which leads to the establishment of positive and negative precipitation anomalies. In this scenario, the objective was to identify Homogeneous Regions of Precipitation Anomalies in the region (1961-2020) and characterize their climatologies. Multivariate and descriptive statistics were applied to monthly precipitation data from the Climatic Research Unit (CRU). The Hierarchical Cluster Analysis was used to execute the regionalization of precipitation anomalies. After determining the regions, time series of the monthly totals were obtained. Sequentially, monthly averages and climatological normals were calculated (1961-1990/1991-2020). Six clusters were identified: regions 1-2 being located at 32º-40ºS; regions 3-4 at 24º-32ºS; and regions 5-6 at 20º-27ºS. Regions 1-2-4-5-6 are affected by regional circulation, supporting the development of periods of drought (wet) in winter (summer). Regions 4-5-6 present climatological aspects of monsoon precipitation. The comparison of climatological normal showed a predominance of greater magnitudes between 1991-2020. In addition, there were some differences, especially, during spring, summer and autumn. The results contributed to a better understanding of the precipitation patterns in the region and can support further investigations of variability and climatic change.