The influence of SAM and ENSO on extreme rainfall over South America

IACOVONE, M. F.; PÁNTANO, V. C; PENALBA, O. C

Christchurch

Conferencia; 13th International Conference on Southern Hemisphere Meteorology and Oceanography; 2022

AMS

Climate extreme events are a topic of interest due to observed and projected changes that have consequences for the agriculture, society, and other sectors. Furthermore, atmospheric and oceanic forcings govern the variability of the climate system at different spatial and temporal scales.The aim of this work is to study the climatology of total accumulated rainfall (pptotal), number of rainy days (rr1), and maximum number of consecutive dry and wet days (CDD and CWD). Moreover, to analyze the relationship between the rainfall indices with El Niño-Southern oscillation (ENSO) and the Southern Annular Mode (SAM), using the Person correlation coefficient. This work is carried out in the trimester October-December, from the period 1981- 2010, in South America.The climatology results show the lowest values of pptotal, rr1, CWD and the highest values of CDD in the northeast of Brazil, the south of Argentina and the Andes region from central Chile to northern Peru, including the Atacama Desert. In contrast, the highest values of pptotal, rr1, CWD and the lowest of CDD were found in Amazonia and La Plata Basin.The signal in extreme events over South America has very significant practical impacts. The regions with stronger ENSO and SAM signal were identified for each extreme rainfall index. In general, the results show that the regions with significant association are La Plata Basin, south of Argentina and the northeast of Brazil. Although the SAM signal is weak, this gets deeper in November. However, the signal is stronger and more extensive spatially during ENSO events.