Antarctic Circumpolar Current transport and barotropic transition at Macquarie Ridge

A deep, high-speed jet within the Antarctic Circumpolar Current (ACC) transports substantial water volumes through a 50 km-wide gap north of Macquarie Island, revealing critical insights into how the ACC navigates large topographic obstacles. The study, combining direct velocity measurements, satellite altimetry, and ocean state estimates, demonstrates that the Subantarctic Front crosses the Macquarie Ridge through this gap, where the ACC becomes more barotropic. The deep jet's acceleration is balanced by ageostrophic pressure gradients, zonal momentum convergence, and dissipation, highlighting the role of local nonlinear processes in the dynamical balance of the ACC. This research provides observational evidence to support theoretical predictions about topographic interactions shaping the ACC's dynamics.

Rintoul, S. R., Sokolov, S., Williams, M. J. M., Peña Molino, B., Rosenberg, M., & Bindoff, N. L. (2014). Antarctic Circumpolar Current transport and barotropic transition at Macquarie Ridge. Geophysical Research Letters, 41(20), 7254–7261. Portico. https://doi.org/10.1002/2014gl061880