Science Meetings

Low-Frequency Thermohaline Variability in the Subtropical South Atlantic Pycnocline During 2002-2013
Kolodziejczyk, N., Reverdin, G., Gaillard, F., and Lazar, A. (19-Nov-15)

Low-frequency variability of salinity is observed in the Subtropical South Atlantic over the period 2002-2013 with the Argo gridded product ISAS. Within the pycnocline, salinity anomalies propagate at a mean speed of 0.04±0.02 m.s-1, the same speed as the gyre mean circulation, from the Agulhas Retroflection region off South Africa (~35°S-20°E) towards the South American coast (~18°S-35°W). After 2010, propagation is still found, but stationary local salinity generation is also found over the Subtropical South Atlantic. This salinity increase is associated with high values of vertical Turner angle below the mixed layer base during late winter. This suggests salt injection resulting from penetrative convective mixing due to air-sea buoyancy loss. These features may have an impact on the low-frequency warm and salty signal produced by the Agulhas leakage in Subtropical South Atlantic and the upper branch of the Atlantic Meridional Overturning Circulation.