The influence of ENSO and Antarctic Oscillation on extreme precipitation over southeastern South America.

The Southeastern South American region (SESA) is one of the AR6 WGI reference regions which is used as an illustration of the interplay between climate variability drivers and regional response. Since most of the agricultural activities take place over this region, its climate variability has a strong impact on society. The region is sensitive to extreme precipitation and puts constraints on water resource management. In recent decades, positive rainfall trends have been detected especially during austral summer. Interactions between the El Nino Southern Oscillation (ENSO) and the Antarctic Oscillation (AAO) also known as the Southern Annual mode, have been well documented indicating the crucial role of ENSO in modulating the AAO phase. In this paper, we explore the interplay between ENSO and AAO and their effect on extreme precipitation over the SESA region during austral spring and summer. Statistical approaches based on extreme value theory (EVT) are applied to daily precipitation amounts to model extreme precipitation, identifying the relative impact of ENSO and AAO. We obtained return values for different phases of ENSO and AAO. We also perform dynamical analysis for sea level pressure and wind field to relate large-scale atmospheric circulation patterns with extreme precipitation.