The “interior-downwelling conundrum” identified in Munk's abyssal recipes has been reconciled by invoking upslope transport within the bottom boundary layer. However, increasing observational evidence suggests that the abyssal ocean—particularly in the Indo-Pacific—is not in a steady state, but instead exhibits widespread isopycnal shoaling. This unsteady regime necessitates a re-examination of the conventional interpretation. In this study, we investigate the dynamics of the abyssal meridional overturning circulation (MOC) using ECCO reanalysis, with the goal of disentangling the advective, sloshing, and diffusive (diabatic) components of the MOC. We find that abyssal cooling leads to isopycnal shoaling, which supports sustained Eulerian upwelling even in the presence of net diabatic downwelling, thus offering a resolution to the interior-downwelling paradox.

abyssal upwelling,ECCO,Indo-Pacifc,Pacific Meridional Overturning Circulation,Munk's upwelling theory