The Salinity and Temperature Fronts in the Equatorial Atlantic Ocean
[28-Aug-2018] Ruiz-Etcheverry, L.A., Maximenko, N., and Melnicenko, O.
Presented at the 2018 Ocean Salinity Science Team and Salinity Continuity Processing Meeting
The Equatorial Atlantic Ocean is a region dominated by the seasonal trade winds and Inter Tropical Convergence Zone (ITCZ). It is also marked by the existence of a strong sea surface temperature (SST) front due to the formation of the equatorial cold tongue. These features are believed to have strong effects on the atmospheric circulation in the region and thus climate. Little, however, is known about the salinity front that became possible to resolve only with the release of high-resolution satellite salinity products. In this study, we use sea surface salinity (SSS) observations from the Aquarius satellite and from the reanalysis model GLORYS to investigate the spatial structure, temporal variability, and driving mechanisms of the frontal SSS feature in the equatorial Atlantic. We also analyze the similarities and differences between life cycles of the temperature and salinity fronts. Our results indicate that more than one salinity front can be identified near the equator: one during boreal winter-spring and another in May-June. The generation and weakening of the fronts are associated with the contrast in physical processes to the south and north (where freshwater fluxes associated with rivers and ITCZ are large) of the equator. Furthermore, the model data analysis corroborates the presence of a strong temperature front during boreal summer and detects a weaker front during fall-winter. The generation and weakening of these features are dominated by the physical processes of the water mass formation to the south of the equator. South of the equator a long-distance advection of saline water, originating from the South Atlantic Subtropical maximum, and its upwelling to the surface play important role while the area north of the equator undergoes freshening events associated with seasonal influences of ITCZ and river plumes from Africa and South America.