Drake Passage & Southern Ocean

Transport and variability of the Antarctic Circumpolar Current in Drake PassageRepeat hydrography on WOCE section SR1b from 1993 to 2000

LADCP results

In 1996, 1997 and 2000 lowered ADCP measurements were made at each CTD station. Near bottom velocities (d) were determined from bottom track data; the error of each bottom velocity is around 0.2 cm/s and have been de-tided using the tidal model of [Egbert, 1994], bathymetry in blue. The section integrated transports due to the geostrophic velocities relative to the bottom and relative to the LADCP derived near bottom velocities are shown in a, b & c. Transport due to the reference velocities is given in each figure.

(a)

(b)

(c)

(d)

persistant westward jet over 20 cm/s on the continental shelf at 60°S
highly variable bottom velocities south of the Polar Front that boost top-to-bottom eddy recirculations to ±25 Sv (b)
Polar Front has eastward bottom velocities of 15 to 20 cm/s
less variable bottom velocities over rough bathymetry north of the Polar Front, with a positive northward gradient of 10 to 15 cm/s between 57°N and 55°N
the average bottom velocities are -1.2, 0.3 and 2.2 cm/s corresponding to transports of -28, 8 and 50 Sv. These are consistent with the analysis of year long near bottom current meter records by [Bryden, 1977], but are larger than the range of absolute transport of 54 Sv derived by [Whitworth III, 1985] from the ISOS.

Abstract

Introduction

Net average baroclinic transport in the Drake Passage

Flux, AABW temperature and frontal position variability

Transport in neutral density layers

Comparison between Drake Passage (SR1) and Australia-Antarctica (SR3) sections

Stuart A. Cunningham, Steven G. Alderson, Brian A. King and Mark A. Brandon

Profiling floats at SOC

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Last Modified: 12/06/02