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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 109,
C05001,
doi:10.1029/2003JC002010,
2004
Upper ocean temperature and the baroclinic transport stream function relationship in Drake Passage
Serguei Sokolov
Antarctic Climate and Ecosystems Cooperative Research Centre and CSIRO Marine Research, Hobart, Tasmania, Australia
Brian A. King
Southampton Oceanography Centre, Southampton, UK
Stephen R. Rintoul
Antarctic Climate and Ecosystems Cooperative Research Centre and CSIRO Marine Research, Hobart, Tasmania, Australia
Ricardo L. Rojas
Centro Nacional de Datos Oceanogrficos de Chile (CENDOC) Servicio Hidrografico y Oceanografico de la Armada (SHOA), Valparaiso,
Chile
Abstract
Repeat hydrographic sections across the Antarctic Circumpolar Current (ACC) in Drake Passage are used to derive an empirical
relationship between upper ocean temperature and the baroclinic transport stream function. Cross validation shows this relationship
can be used to infer baroclinic transport (above and relative to 2500 m) from expendable bathythermograph (XBT) temperature
measurements with an error of a few per cent. Transport errors of less than 2 Sv are obtained if temperature at depths between
600 and 1600 m is used to define the relationship. Temperature at depths above 300 m provides an unreliable index of transport
because of variability in temperature-salinity (T-S) properties produced by air-sea interaction. The scatter in the relationship between temperature and stream function from
repeat observations along a single line is similar in magnitude to the scatter observed when data from the broader Drake Passage
area are considered. In both cases, variability about the mean temperature-stream function relationship reflects advection
of water with anomalous T-S properties. The tight relationship between temperature and stream function in Drake Passage and south of Australia suggests
baroclinic transports can be inferred from XBT temperatures with high accuracy in the Southern Ocean, providing a cost-effective
means of monitoring ACC variability. However, care must be taken at the end points, particularly in the Drake Passage where
the strong flow of the Subantarctic Front sometimes lies over the continental slope.
Received 18
June
2003;
accepted 13
February
2004;
published 1
May
2004.
Index Terms: 4207 Oceanography: General: Arctic and Antarctic oceanography; 4223 Oceanography: General: Descriptive and regional oceanography; 4512 Oceanography: Physical: Currents.
Read Full Article (file size: 1108230 bytes) Cited by
Citation: Sokolov, S., B. A. King, S. R. Rintoul, and R. L. Rojas
(2004),
Upper ocean temperature and the baroclinic transport stream function relationship in Drake Passage,
J. Geophys. Res.,
109,
C05001,
doi:10.1029/2003JC002010.
Copyright 2004 by the American Geophysical Union.
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