Bottom water warming in the Pacific Ocean in an ocean state estimation using tidally induced mixing parameterization

Decadal repeat of modern, high-quality, full-depth, hydrographic section observation have revealed the basin-wide warming of the bottom water in the Pacific Ocean, which cannot be neglected for precise estimation of the global heat balance. It is likely that this warming results from a small imbalance between the larger advection and diffusion terms. We have developed a new quasi-global four-dimensional variational data assimilation system using two parameterizations for tidally induced vertical mixing, and are conducting a long-term data synthesis experiment. We investigate the bottom water warming in an ocean state estimation dataset obtained through the experiment, and discuss its mechanism.