Volume Transport Variability of the Atlantic Meridional Overturning Cells at 34.5°S

Variations in the Atlantic Meridional Overturning Circulation (AMOC) are known to have important impacts on global scale climate phenomena. Its particular structure in the South Atlantic is thought to control the stability of the entire AMOC system. Thus, significant resources have been invested in observing the AMOC in the South Atlantic over the past decade. Multiple years of full-depth daily observations from moored instruments at 34.5°S are used to calculate the meridional transports near the western and eastern boundaries, as well as basin-wide interior transports, via dynamic methods. These geostrophic transport estimates can be combined with Ekman transports derived from satellite wind products to yield estimates of the daily total transports. Analysis of the AMOC volume transport using all available moored instruments from 2013 to 2017 allows us to quantify for the first time the daily volume transport of both the upper and abyssal overturning cells at 34.5°S. The variability of these flows is characterized in unprecedented detail, illustrating that transport variability of the abyssal-cell is largely independent of the transport variability in the upper-cell. Analysis of this new data set is crucial for improving our understanding of the temporal and spatial scales of variability that governs AMOC related flows, and for disentangling their respective roles in modulating its overall variability and latitudinal connectivity.