Walter Munk's seminal work, known as the 'abyssal recipes', introduced a foundational framework for understanding the upwelling of abyssal waters. While it has inspired numerous investigations into deep-ocean processes from theoretical, laboratory, and field perspectives, it has also faced challenges when compared to decades of direct observations. Two particularly intriguing paradoxes have emerged: the diffusivity dichotomy and the conundrum of interior downwelling.

To address these issues, the bottom boundary layer (BBL) upwelling theory has been developed since 2016, led respectively by R. Ferrari and T. McDougall. Their model incorporates an interior downwelling layer and an upwelling BBL along the slope seafloor. However, the BBL upwelling theory cannot explain abyssal upwelling in flat-bottom oceans or coarse-resolution models.

In this study, we propose a new mechanism for abyssal upwelling and test it with several 4000-year simulations using the MITgcm. The results demonstrate that upwelling processes are independent of the vertical profile of mixing intensity and bottom topography, casting doubt on the prevailing BBL upwelling theory.

Munk's abyssal recipes, overturning circulations, MITgcm