The Meridional Overturning Circulation (MOC) is a critical component of the climate system, playing key roles in heat and material transport, deep ocean ventilation, and global water mass distribution and stratification (Talley, 2013). MOC deep waters form in several regions of the subpolar North Atlantic and of the Antarctic margins, from which they are exported globally in complicated patterns, carrying to their destinations the signatures of their air-sea interactions prior to ventilation. Monitoring and deducing the global MOC transport is thus crucial for understanding of ocean circulation and climate variability. Traditionally, the MOC was estimated using geostrophy and inverse methods from ship-based hydrographic measurements (Wunsch, 1996). However, the sparseness of ship hydrography in time and space limits the recoverable information, and can lead to severe aliasing, for example, of temporal variability (Frajka-Williams et al., 2019). In the last two decades, dedicated in situ monitoring arrays have been put in place at several latitudes, although only in the Atlantic Ocean. Several arrays span the width of the basin: the RAPID-MOCHA array at 26. 5°N (Cunningham et al., 2007;