A curious local surface salinity maximum in the northwestern tropical Atlantic

This seasonal tropical SSS maximum, which is confirmed by comparison to in situ observations, is centered at 8°N, and is up to 0.5 psu saltier than the surrounding water despite its location in the latitude band of the highly precipitating Intertropical Convergence Zone.

Its existence seems to be the result of the differing phases in the seasonal variations of Amazon discharge and ocean currents. In late boreal fall/winter, when the discharge is at its minimum, but the North Brazil Current (NBC) and its retroflection are still present, a mixture of high-salinity water of equatorial and South Atlantic origin is transported along the shelf break by the NBC retroflecting into the western part of the North Equatorial Countercurrent (NECC).