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

Satoshi Osafune1, Shuhei Masuda1, Nozomi Sugiura2, Toshimasa Doi1 and Tadashi Hemmi3, (1)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (2)Japan Agency for Marine-Earth Science and Technology, Research and Development Center for Global Change, Yokosuka, Japan, (3)JAMSTEC, Japan
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.