Assuming the vertical advective-diffusive balance, we calculate the meridional overturning circulation of the deep Pacific based on the observed density field. In addition to the global distribution of diapycnal diffusivity in the pycnocline, bottom-intensified mixing that follows a Gaussian distribution with depth is taken into account. When diapycnal diffusivity in the pycnocline is assumed to extend uniformly to the bottom, the northward transport of the Lower Circumpolar Deep Water (LCDW) across the equator is only 1 Sv. When the bottom-intensified mixing is incorporated, the meridional overturning circulation increases, decreases, or even reverses depending on the vertical gradient of diapycnal diffusivity. The northward transport of the LCDW crossing the equator becomes comparable to the estimates from previous current meter moorings as well as hydrographic surveys only when the mixing extends well above the rough ocean bottom and hence the vertical gradient of diapycnal diffusivity is small.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)