Relações de larga escala entre a Temperatura da Superfície do Mar do Oceano Atlântico Sul e a precipitação continental na América do Sul no período de 1901

Abstract

Large-scale interactions between the ocean and the atmosphere are essential to characterize climatic variability over time. Several studies analyze the variability of the sea surface temperature (SST) of the South Atlantic Ocean and the continental precipitation of the South America with samples under 50 years old, due to the lack of observed data and longer reanalysis in the Southern Hemisphere at the time they were published. The creation of centenary reanalysis by NOAA and ECMWF has made it possible to study climatic variability over a long period. Therefore, the objective of this work is to analyze large-scale relationships between the SST of the South Atlantic Ocean and to represent its effects on continental precipitation in South America in the period from 1901 to 2010. The multivariate statistical analysis of the empirical orthogonal functions (EOF) was applied to reanalysis data to obtain the variability of the sea surface temperature in the South Atlantic Ocean and continental precipitation in South America, in addition, the South Atlantic dipole index, the dominant mode of coupled variability in the South Atlantic Ocean, and the large- scale monsoon index in South America (LISAM) were calculated to represent the main large-scale characteristics of SST and precipitation in the specific area of this present work. The reanalysis ERA-20C, ERA-20CM, CERA-20C and NOAA20CR showed similar spatial patterns of variability in the variables analyzed, and the coupled centenary reanalysis CERA-20C of the ECMWF proved to be statistically more reliable in the representation of continental precipitation data in South America. The correlation of the South Atlantic Dipole index with continental precipitation in South America showed the highest values in coastal areas in the northeast, southeast and south regions of Brazil. The effects of the South Atlantic dipole on continental precipitation anomalies in South America were more evident on the seasonal and multidecadal scale and act more intensely in the northeast and southeast regions of Brazil. The Rodionov test applied to the rainy and dry seasons of the Monsoon system in South America pointed to stability in those seasons, with few changes in the regime of the average pattern of precipitation in the period from 1901 to 2010. Based on the literature reviewed, this is the first work that has done a climatological analysis of the effects of SST of the South Atlantic Ocean on the continental precipitation of South America in multidecadal, decadal, seasonal, monthly and daily time scales in the period from 1901 to 2010.