Antarctic Bottom Water Flow in the Western Part of the
Romanche Fracture Zone Based on the Measurements in October
of 2011

R. Yu. Tarakanov^a, N. I. Makarenko^b, and E. G. Morozov^a

^a Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia

^b Lavrentiev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia

e-mail: rtarakanov@gmail.com

Received September 6, 2012

Abstract—The properties of the Antarctic Bottom Water flow in the region of its inflow to the channel of the
Romanche Fracture Zone at 2210–2230 W are studied on the basis of CTD and LADCP profiling in the
western part of the equatorial fracture zone. A deep water cataract was found at the sill over the southern wall
of the fracture with a depth of approximately 4600 m, which is associated with the abyssal flow, whose potential
temperature is lower than 1C. The inflow of water into the channel of the fracture in this temperature range is
fully localized over this sill. The minimum potential temperature recorded in 2011 near the bottom was equal to
0.51C, which is lower approximately by 0.12C than the minimum temperatures ever measured in the western part
of the fracture. The water transport in the cataract was estimated at 0.2 Sv (1 Sv = 10⁶ m³/s), which is approximately
30% of the known estimates of the total transport of Antarctic Bottom Water ( < 1.9C) through the fracture.
The extremely high intensity of the cross isothermal mixing in the cataract region was found. The analysis of
the bottom topography data, including the historical WOD09 dataset, shows that the inflow of water with 1.00
< < 1.70C into the channel of the fracture is most likely fully localized in a few passages in the region of the
survey in 2011, while the water exchange with the abyssal waters with > 1.70C through the Romanche Frac-
ture Zone between the West and East Atlantic can also occur through the depressions in the southern and north-
ern walls of the fracture in the region of the Vema Deep.

DOI: 10.1134/S0001437013050147

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