A HYCOM representation of the South Atlantic and its impact on the tropical ocean

Abstract

Recent work suggests that changes in the South Atlantic (SA) impact the tropical regions. The potential effects of these changes on the ocean circulation and the transport trends in the tropical Atlantic are studied here with the outputs for the period 1960‐2010 from the Hybrid Coordinate Ocean Model, an ocean circulation model with 1/12± resolution and 22‐isopycnal layers. This circulation model is forced with NCEP/NCAR monthly composites of surface winds and atmosphere‐ocean heat and freshwater fluxes. Changes in the barotropic transport and the sea surface height are evident from 1960 to 2010, with the largest variations taking place in two regions: the Agulhas Retroflection and the North Brazil Current. The model suggests that there has been an increase in the Agulhas leakage into the SA during the last decade, which has led to a density gain of the upper SA layers and to a positive anomaly in latent heat flux in the western boundary of the tropical Atlantic