Analysis of correlations between the South Atlantic Convergence Zone and Climate Indices Derived from the Pacific and Atlantic Oceans for Evaluating Teleconnections

The South Atlantic Convergence Zone (SACZ) is one of the most important phenomena that influences the precipitation patterns in Brazil’s Southeast and Midwest regions during the spring and summer. These regions play a major role for the country’s economy, particularly in terms of agriculture and industrial production. It is estimated that the SACZ is responsible for approximately 25% of the total volume of rain in Southeast Brazil from October to April. The conditional probability of a natural disaster occurring when the SACZ is present in the region is around 24%, while, in the case of a disaster occurring in the Southeast, the conditional probability of observing the presence of SACZ is 48%. This work provides an initial understanding of how different teleconnection patterns can influence the configuration, position, and intensity of the SACZ. The goal is to investigate potential correlations between the SACZ index, the El Niño Southern Oscillation (ENSO) indexes, the Atlantic Sea surface temperatures (SST) between Central America and Africa, the Brazil-Malvinas Confluence (BMC) and the Antarctic Oscillation (AAO). For the SACZ indexes, the monthly data was derived by summing the values for each month. This process utilized data spanning from 1980 to 2010 to establish the monthly climatology. The monthly indexes and anomalies were compared with the monthly climatology values from January 1999 to December 2022. For daily indexes of BMC, Niño1+2, Niño 3, Niño 3.4, Niño 4, Atl_N, Atl_NL, Atl_C and Atl_CL sea surface temperature (SST) anomalies were referenced against a climatology spanning from 1971 to 2000. In these cases, monthly data was obtained through the average of the daily indexes. Finally, AAO indexes were already obtained monthly. In this case, the time series were normalized using the standard deviation of the monthly index, based on the 1979-2000 period. Three Pearson correlations were calculated monthly for the period from 1999 to 2022. These correlations were evaluated for the average from October to March, October to December, and from January to March. The preliminary results showed that colder anomalies of the Equatorial Pacific (La Niña), the North Equatorial Atlantic, and the CBM, in conjunction with a positive phase of the AAO and warmer waters of the Central Equatorial Atlantic, are associated with the occurrence and configuration of the SACZ (and vice versa). This signal is most pronounced in the period from October to December and during the October to March timeframe, while it weakens in the months from January to March.