Y. Fukamachi et al., Nature Geosci., 3, Strong export of Antarctic Bottom Water east of the Kerguelen Plateau

Nature Geoscience, 3 (2010) 327-331, published online: 25 April 2010; doi: 10.1038/ngeo842

Strong export of Antarctic Bottom Water east of the Kerguelen Plateau

Y. Fukamachi^1,*, S. R. Rintoul^2,3,4, J. A. Church^2,3,4, S. Aoki¹, S. Sokolov^2,3,4, M. A. Rosenberg⁴ and M. Wakatsuchi¹

Abstract

The primary paths for the transport of Antarctic Bottom Water from the Southern Ocean into the global ocean are the deep western boundary currents east of the Antarctic Peninsula and the Kerguelen plateau¹. Previous ship-based observations documented distinct water properties and velocities associated with a deep western boundary current in the Kerguelen region^{2, 3, 4, 5, 6, 7}, but the mean flow is as yet unconstrained. Here we report measurements from a coherent array of eight current-meter moorings that reveal a narrow and intense equatorward flow extending throughout the water column just east of the Kerguelen plateau. Velocities averaged over two years exceed 20 cm s⁻¹ at depths of about 3,500 m, the strongest mean deep western boundary current flow yet observed at similar depths. We estimate the mean equatorward transport of water colder than 0 ^°C at 12.3±1.2×10⁶ m³ s⁻¹, partially compensated by poleward flow. We also estimate the net equatorward flow of water colder than 0.2 ^°C at about 8×10⁶ m³ s⁻¹, substantially higher than the 1.9×10⁶ m³ s⁻¹ reported from the boundary current that carries dense water from the Weddell Sea into the Atlantic Ocean north of the Falkland plateau⁸. We conclude that the Kerguelen deep western boundary current is a significant pathway of the global ocean’s deep overturning circulation.

1. Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
2. Centre for Australian Weather and Climate Research—a partnership of the Bureau of Meteorology and CSIRO, Hobart, Tasmania 7000, Australia
3. Wealth from Oceans Flagship, Hobart, Tasmania 7000, Australia
4. Antarctic Climate and Ecosystem Cooperative Research Centre, Hobart, Tasmania 7001, Australia

*Correspondence e-mail: yasuf@lowtem.hokudai.ac.jp

Link:  http://www.nature.com/ngeo/journal/v3/n5/abs/ngeo842.html