The South Atlantic sub-tropical dipole mode since the last deglaciation and changes in rainfall

The South Atlantic subtropical dipole (SASD) has an impact on South American rainfall particular during its negative phase when continental precipitation in the northern part of the continent is enhanced. Relying on a series of single forcing transient simulations since the last deglaciation, we differentiate the relative role of meltwater, orbital, ice-sheets and greenhouse gases on the variability of rainfall in South America and links to the SASD. Results indicate that the meltwater forcing is the predominant driver of SASD variability. Wavelet analysis shows that most of the energy for the SASD at lower frequencies (∼ 5 kyr) comes from the meltwater discharge at cold events such as the Heinrich-1 cooling ∼ 17 ka and the Younger-Dryas ∼ 12.9 ka. Large rainfall changes in Northeastern Brazil can be attributed to changes in the South Atlantic sea surface temperature latitudinal gradient and South Atlantic Northward heat transport driven by the meltwater discharge.