Impact of sea surface temperature anomalies on the Jet Variability and Atmospheric Blocking over the South America Sector

Atmospheric blocking represents an important feature for regional climate and weather patterns and plays an important role in extreme events, such as heat waves and droughts. In spite of its importance, our knowledge of the physical mechanisms inherited to intensity and frequency of atmospheric blocking is very limited, particularly for the Southern Hemisphere. In this study, we investigate the link between precipitation over southeast South America (SESA), jet variability and atmospheric blocking over the eastern South Pacific and South Atlantic sector, using reanalysis data products. Preliminary results show that blocking episodes that suppress precipitation over the northern part of SESA are related to presence of anomalous anticyclones located eastern South Pacific. Moreover, atmospheric blocking in the eastern South Pacific is associated with the formation of cutoff low-pressure systems, which in turn generate significant precipitation events in the southern part of SESA. The role of the sea surface temperature anomalies on atmospheric blocking in the South Pacific/South Atlantic sector is determined by investigating the relationship with the three dominant remote modes of climate variability for this region, namely El Niño – Southern Oscillation (ENSO), South Atlantic Dipole Mode (SASD) and Southern Annular Mode (SAM).