Interannual Variability of the Latitude of Separation of the Brazil Current: Teleconnections and Oceanic Rossby Waves Propagation

BODNARIUK, NICOLÁS; SIMIONATO, CLAUDIA G.; SARACENO, MARTÍN; OSMAN, MARISOL; DIAZ, LEANDRO B.

Journal of Geophysical Research: Oceans

Wiley

Año: 2021 vol. 126

2169-9275

The latitude of separation of the Brazil Current (LSBC) variability is analyzed with a view to unveiling the physical mechanisms that modulate the turning point of the Brazil Current at low frequencies. The global  ocean reanalysis ORAP5.0 spanning the period 1979?2013 is employed  for this purpose. Three characteristic periodicities of the LSBC  variability are found on the basis of a Singular Spectrum Analysis: 2, 4   and 10 years. Lagged sea surface height (SSH) correlation maps relate  these modulations to Rossby wave propagation. According to these  maps, the biennial signal might be triggered by the Atlantic Niño and the  Indian Ocean Dipole. In the last case, SSH anomalies propagate around the southern tip of Africa, connecting the Indian and Atlantic  oceans. Correlation maps suggest that the 4-year signal is triggered by  both the Atlantic Niño and the ENSO in the equatorial Pacific Ocean. The  ENSO-related anomalies travel through the Indonesian Throughflow  along the western Australian coast, where Rossby waves  are excited. These anomalies propagate to the eastern coast of  Madagascar and feed into the Agulhas Current, eventually leaking into  the Atlantic basin. Finally, the decadal signal is associated to the leading  mode of decadal variability of the South Pacific Ocean. SSH propagating  patterns derived from ORAP5.0 data are also obtained with satellite  altimetry during the overlapping period (1993?2013), which strengthens  confidence in our results. The association of the LSCB modulations to  characteristic climate variability modes suggests that the position of the  LSCB could be predicted.