“…Closing the sealevel budget (Leuliette, 2015;WCRP Global Sea Level Budget Group, 2018) requires accurate knowledge of ocean bathymetry (Woelfl et al, 2019), ocean sea level (Ponte et al, 2019), barystatic changes (mass of freshwater added or removed; Palmer et al, 2019), and thermostatic changes (e.g., changes in heat content; Meyssignac et al, 2019). Multipurpose acoustic observing systems will contribute to improved monitoring of volume, freshwater, and long-term heat fluxes, as well as monitoring long-term heat content changes at basin-scale, as well as in specific regions of global importance (e.g., Indonesian throughflow; Ravichandran, 2011;Sprintall et al, 2019). Multipurpose acoustic systems can provide ground-truth for ecosystem modeling and forecasting.…”