Seasonal variability of the Atlantic Meridional Overturning Circulation at 11° S inferred from bottom pressure measurements

Abstract. Bottom pressure observations on both sides of the Atlantic basin, combined with satellite measurements sea level anomalies and wind stress data, are utilized to estimate variations Meridional Overturning Circulation (AMOC) at 11∘ S. Over period 2013–2018, AMOC its components dominated by seasonal variability, peak-to-peak amplitudes 12 Sv for upper-ocean geostrophic transport, 7 Ekman 14 transport. The characteristics observed cycles compared results from an ocean general circulation model, which is known reproduce variability Western Boundary Current longer timescales. zonally integrated velocity in upper 300 m controlled eastern boundary, while 500 depth contributions western boundaries similar. model tends underestimate depth, especially translates into In S governed, besides transport basin. contribution basin cycle instead comparably weak, as interior related local curl forcing mainly compensated Current. Our analyses indicate that some uncertainties our estimates result technical aspects observational strategy or processes not being properly represented particularly relevant resulting