Impactos do El Niño 1997/1998 sobre a dinâmica da Corrente do Brasil

Abstract

El Niño-Sul Oscillation (ENSO) is a widely studied phenomenon of oceanatmosphere interaction, due to its global climate impact. The phenomenon has two phases, a hot phase (El Niño) and a cold phase (La Niña). ENSO remotely influences the South Atlantic's Subtropical High (SASH) winds pattern, which is the main actor forcing the surface South Atlantic Subtropical Gyre (SASG). On the west edge of the SASG is present the Brazil Current (BC), which has its superficial drainage derectally influenced by this atmospheric feature. Therefore, understanding the impact of ENSO over the SASG dynamics would be an important contribution to understanding ENSO potential impact over BC flow. For this purpose, the section 25ºS was analyzed in order to investigate potential changes in the volume transport and in the heat transport of the BC that could be associated with changes in the local Wind Stress Curl field. To correlate the probable impacts of El Niño in the oceanic and atmospheric variables the multivariate ENSO Index (MEI) was used. The obtained results demonstrated that the BC transport is influenced by El Niño 97-98 eighteen months after the onset of the phenomenon and cross-correlation between transports with MEI submitted a maximum correlation of approximately 46%.