Meetings: Documents

The South Atlantic Subtropical Gyre Position the Larger Scale Ocean and Climate System
[19-Nov-15] Giulivi, C.F. and Gordon, A.L.
Presented at the 2015 Aquarius/SAC-D Science Team Meeting
Using a diverse set of observational and model data we examine the seasonal to decadal variability of the South Atlantic subtropical gyre in the context of: changes in the gyre's relationship to the larger scale ocean and climate system; the response of the gyre interior to its boundary including of interocean exchange. The subtropical anticyclonic gyre may be envisioned as a triangle: the SEC bifurcation at the NW corner that directs water into the upper limb of the AMOC or into the southward flowing Brazil Current; the Agulhas leakage (warm/salty ‘thermohaline bridge’) at the SE corner; the Brazil-Malvinas Confluence at the SW corner; with a cyclonic gyre, the Angola Dome, stretching along the SE to NW limb. South of the bifurcation, against the western margin, we find the SSSmax. Using Aquarius SSS with other atmospheric/ocean data we describe the maximum seasonal/interannual variability in relation to the latitudinal migration of the bifurcation, to wind stress curl changes at the core of the gyre and to the influx of salty waters through the ‘bridge’. On decadal scales and across the basin, we identify that positive sea level anomalies (SLAs), higher surface/upper thermocline salinities and a positive curl prevail after early 2000s.